"Mark! There you are! I'm so sorry!" her voice said.

The micro-sized boy breathed a huge sigh of relief. She noticed him. After being tortured by her farts and gargantuan asshole he had finally been spared from Nikki. Her unawareness to just how insanely small she had shrunken him down to had nearly killed him, but at long last he was saved. Even with the horrible stench surrounding him Mark smiled, almost chuckling to himself from how crazy this situation was. Maybe it was the adrenaline still rushing through him or it was the intense wave of emotions that he was feeling after finally being found, but he was happy instead of furious. Of course he knew Nikki didn't actually want to hurt him, it was just her carelessness was downright deadly.

"I'll get you out of there right away, okay?" Nikki said, looking straight down at him. "I had no idea that you were shrunken THAT small! I swear, I only meant to make you like an inch or two small, not... whatever the hell that is."

Mark wanted to tell her it was okay. Her voice was different than usual, she actually sounded concerned for his safety. After being teased so ruthlessly in her ass he was sort of expecting her to laugh at his toilet-drifting position, but that wasn't the case at all. The possibility of actually killing her friend with her ass must have crossed Nikki's mind, and it seems like she was still feeling rather shook. Mark looked at the enormous bowl surrounding him and felt relieved. Had Nikki been less careful he could have been in this toilet under much much more harrowing circumstances.

"Here, grab on to this!"

His giantess friend had unrolled a giant strip of toilet paper and lowered it down into the bowl. The paper dipped into the water, soaking itself immediately as it descended under the surface. Nikki wiggled it a bit towards Mark and lifted it back out, his minuscule speck of a body sticking to the damp material like fly paper. He didn't really need to hold on to anything, the tension of the gigantic water droplets held him in place just fine. After finally exiting the toilet Nikki brought the wet paper into her hands and carefully retrieved Mark's body by sticking him to the tip of her finger. Mark felt the cool air surrounding his naked body and began to shiver. Nikki gently examined the pad of her finger up close. It was scary to have her massive eyes looking at him, studying his almost invisibly-small shape. When she spoke it was loud like thunder.

"Holy shit you're so small now! How did you even survive? You were in my asshole the whole time right? Even when I was farting and squeezing it?! Jesus..."

The most she could see was Mark's puny head nodding in agreement.

"Ugh... I'm so sorry! I really didn't know I had made you that small! Seriously, I only wanted to make you like... the size of a toy or something! It was just to tease you. I swear!"

Mark nodded again, trying to get across that he understood.

"I don't really have anywhere I can keep you safe, so I'm just going to use the portal device to send you home okay?"

Using her other hand she fished the device out from her bag.

"Unless... you want to spend the rest of the day back in my ass again?"

Nikki's mouth frowned a little after making that joke. It was clear she felt bad immediately after the words came out of her mouth. She couldn't help herself from teasing Mark, it was in her nature or something.

After that she set the coordinates to exit the portal back at Mark's house, doubling checking to make sure the numbers were right this time. She had to reverse the sizes of the portals from how they were before, to make sure when he came back out he'd be the same height he started out as. Due to this, the portal was so small that Nikki couldn't really reach her finger all the way through. Instead, since she was still sitting on the toilet, she tried a "dropping" approach. The massive teen placed the small portal between her legs, at the stretched-out hammock of her panties. Mark looked down as she brought her finger closer, at the center of her gigantic underwear was a small whirling portal leading to one of the rooms in his house. Nikki waggled her finger a little, allowing Mark to drop down in free fall for a second, before landing back inside his house.

"Landing" might not have been the appropriate word for it, it was more like a painful crash onto the hard tiled floor. Nikki was considerate enough to send Mark back to the bathroom of his home, where he could start to clean himself up. Even so, the fall really hurt, and it took a couple seconds for him to stand back up. It wasn't nearly as bad as the torture he went through inside her giant anus, but his knees still ached. Thankfully his parents weren't home to hear the loud thud he made coming in.

Despite having a bath in toilet water, his body reeked to high heaven. He was only just freed from an unwanted tour of Nikki's bowels, the disgusting waste and slime that had nearly drowned him to death had imprinted its smell onto his skin. Being farted on by a school girl's ass thousands of times the size of your own body would do that to you. Mark took one whiff and nearly wretched, he needed several scrubs over to make himself feel clean again. Luckily the shower was right here.

Mark ran the water hot, really hot. He must have used up half a bottle of body soap, smearing himself in the bubbly, fragrant scents over and over again. He scrubbed so hard his skin felt almost raw. His hair was the hardest part, getting Nikki's fart stink out of that took at least 20 minutes alone. When he was finally done though he felt like a new man. He'd never had a shower that long and that focused, it felt like he had been the freshest in his life. The bathroom mirror was completely fogged up with steam as he dried himself off, the whole room was dripping with condensation thanks to the shower running so hot for so long.

Mark returned to his room to get dressed. There was still a faint trace of Nikki on him but he was confident it wasn't enough to stain his clothes. With a big sigh he laid down on his bed and started browsing his phone. It was only just the starting hours of the afternoon and yet he felt exhausted. Fighting for his life inside his friend's gigantic anus was a lot to go through. After a couple minutes he put his phone down and rested his eyes. Just a short nap was what he needed...

GGRRRRRGGLLLRRRGGG...

A tremendous sound jolted Mark back awake. It had been about a half an hour since he passed out. The bellowing noise sounded like an earthquake was happening around him. Right away he got up from his bed and looked around in confusion. His room was still how he remembered it, but something felt wrong. Whatever the noise was, it was coming from the bathroom, so Mark cautiously went to investigate.

The steam left over from his shower had since dissipated. Most of the mirror had become unfogged too, and what it revealed was something he wasn't mentally prepared for. Mark didn't notice it earlier thanks to all the shower steam but the portal Nikki had opened was still on and running. The whirling exit gateway was hanging there on the bathroom ceiling, and sitting on the other side was Nikki's colossal asshole. Since she placed the entrance portal at the bottom of her panties, when she put her underwear back on, it caused the tiny circular gateway to line up with the wrong place. Now Mark was staring at her huge anus once again. It was just as enormous in magnitude as it had been before, only now it was exposed to the vulnerable walls of his bathroom. Mark remembered just how gigantic her hole was from when he was caught inside of it. Her anus's width far exceeded the entry point of the portal, it was big enough to swallow his whole house and maybe the next few down the road. Unfortunately for him, where he was looking at right now was the dead center of her butthole, where all the oily wrinkles met into one dark crevice.

Suddenly the massive beast twitched. Its sticky folds clenched together just on the other side of the portal, making a gross wet smacking noise. Then right after that they bulged back outwards, pushing out even further than they had before. For the teenage girl on the other side this action wasn't even anything of note, her asshole muscles were shifting on such a small scale that it didn't even register in her mind. For Mark however this minor movement made his entire house shake. Framed photographs rattled against the walls, his toothbrush leaning inside its holder trembled with enough force that it did a little dance. Then came the noise. A deep groaning sound roared from the orifice above Mark. It gurgled loudly and angrily, even greater than when it had woken him up. Far beyond the twitching maw of Nikki's oily sphincter, her bowels were dealing with some large gastrointestinal pressure. The bubbling payload of air snaked its way through her sexy body, pushing past the many obstacles in her digestive system to seek a way out. Mark recognized the sound immediately and knew it wasn't an empty threat.

He ran back to his room and grabbed his phone. He dialed Nikki's number from her contact info, praying that she would pick up. While the phone rang he raced back to the bathroom where the giant anus was still waiting. There was no answer. Shit. He tried texting her, all caps: "TURN OFF THE PORTAL NOW!!!" Sent. Anxiously Mark waited for a reply, sweating with the phone in his hands and the ridiculously oversized butthole looming above. The seconds went by agonizingly slow, reaching a full minute until Mark came to terms that Nikki wasn't looking at her phone at all.

At school, Nikki's phone was currently zipped inside her bag. The emergency toilet meeting she had with Mark resulted in her running late for class, and so she stuffed her phone away with her books without even realizing. The phone silently vibrated when he called, and when he sent her a text the notification light flashed for no one to see. Meanwhile Nikki was sitting at her desk, paying attention in class without being the least bit aware of Mark's predicament. Her huge shapely ass was pressed down comfortably into her seat, while her cute panties were formed flat against her buttcrack. There were no signs of her getting up to go anywhere soon, her asshole and the tiny portal underneath it were locked in place under the weight of her giant body.

Mark didn't know how else he could contact Nikki. If he didn't do something fast her anus was going to blast his house with a mega-sized fart. Another rumbling growl came from Nikki's ass, this one sounded serious. Back at school she felt her stomach gurgle a little. She put a hand to her tummy and felt the familiar pressure rising deep within her insides. All she had to do was push her hand a bit and the gurgling noises returned. A heavy weight entered her bowels, and she knew that a fart was coming. Her anus clenched in anticipation. She was still in the middle of class and she had to be careful. Nikki knew how to let her gas out quietly during lessons, but she had to focus her ass muscles to do it right. Meanwhile Mark's notification message on her phone was still blinking inside her bag.

The young man's bathroom shook even harder as Nikki began to focus on her butthole. The incredible lumpy folds of her anus tightened together inside her panties, exerting strength onto the entrance to the portal, and by extension Mark's whole house. Objects were shaking and falling all over the place, but there was no time to pick them up. Mark needed to get Nikki's attention more than anything else. He stood on top of the bathroom counter, his feet planted on either side of the sink, reaching his arms up to go through the portal. Just on the other side Nikki's anus was flexing, holding itself closed as the gas filled up. Back in her classroom her large butt purred into the chair. Hot gurgles of methane were passing through her colon, underneath her skirt a whole cacophony of bubbly fumes were collecting together. Nikki could feel that the gas was nearly at her backdoor, it was almost ready to come out...

Mark's hands went through the other side of the portal, touching Nikki's twitching anus. He grabbed one of her meaty anal wrinkles with both hands, it was oily and thick and moving with a mind of its own. The hulking band of flesh throbbed and pulsated with the rest, clenching together with the other ripe folds to keep her hole shut tight. Mark could barely keep his grip on the girl's hot flesh, he squeezed and pulled at it as hard as he could, but his minuscule struggles didn't even register to his giantess friend. Her enormous butthole continued to flex and tighten as if he wasn't there. Mark grew desperate and wild. He needed to get her attention NOW.

He thrashed and pounded at the resilient flesh mounds, battering them as well as he could muster without falling off the bathroom counter. With open palms he slapped the girl's meaty skin, jabbing and hitting it while screaming for her to notice. In desperation he grabbed onto the anal wrinkle and held it as tight as possible, kicking his legs off the bathroom counter to yank it down with his full body weight. The natural sweat of her ass made it hard to grip but Mark hung on regardless.

Just then the giant anus started to let up. Mark thought it was finally succumbing to his attack but then the whole thing puckered outwards. Nikki's fat beefy wrinkles expanded flagrantly from her ass, the sudden shift in form caused Mark to lose his grip. He fell down to the bathroom's floor tiles, bashing his hip off the counter on his way down. Nikki's farthole bulged out towards him, her puckered anal folds domed out so far that they came through the other side of the portal. Mark's house creaked as the brewing storm shuddered through Nikki's ass, the buildup of pressure had reached its limit. Nikki leaned her massive ass back into her chair and prepared herself for release. Her mouth closed shut as she held her breath, focusing all her attention on relaxing her asshole just slightly...

Absolute hell burst through the portal and into Mark's house. The raging inferno of teenage girl gas blasted the door to his bathroom wide open, knocking it right off its hinges. The window going outside shattered into pieces, the shower curtain was ripped clean off, and Mark's poor body was slammed down into the hard tiles once again. Nikki's hot misty fart sprayed all over the place, violently erupting out of the portal and shooting her rancid gas throughout her friend's house. She was just parting her anal lips a little, carefully widening her asshole so that her fart would come out quietly, but the result came tearing visciously through the other side. Paintings flew off the walls, dishes fell to the floor and shattered, the whole building was vibrating from her gas, and it just wouldn't stop.

The tremendous fart droned on, flattening Mark against the floor. He couldn't move an inch as his friend let her gas out, the rampaging anal winds blew so hard that it felt like he was being crushed by them. Nikki's release was hot and potent, the muggy shittty air that had been cooking inside her bowels for hours was now brazenly spreading through the rooms of his home. It smelled atrocious, her breakfast smoothie, eggs, and toast had all been transformed into a steamy powerful bout of gas that couldn't be stopped. Bits of moisture sprayed all over Mark's body, splattering the bathroom walls. The heat was sweltering, it was so hot that it made the bars of soap start to melt. Nikki sighed as she let it all out. Her gas was hissing out quietly like she hoped, and the release of pressure felt comforting to her butt.

After a few more grueling seconds she was done, and her asshole closed back up. Mark's house was left a disaster zone, it reeked to high heaven and the damage was strewn about everywhere. As he weakly stood up from the spot where he had been pinned down he noticed a dip in the floor. Nikki's fart was so intense it actually bent the bathroom tiles, creating a wide bowl in the floor where it had touched down. Mark coughed and gagged on the terrible stench, it burned at his lungs. Slowly he limped himself around the house, opening all the windows to let Nikki's gas air out. He needed to have another long shower to get her smell off him again, but first he needed to clean the house before his parents got home.

The next several hours were spent picking up everything that had been knocked over and broken because of the fart. Mark cleaned room by room, fixing all the major problems before finally cleaning himself off. The raw air from Nikki's ass started to filter out after a couple hours, but the lingering stink would remain for days. A heaping amount of cleaning products were going to be needed to get things smelling fresh again. When his shower was done he went back to tidying, taking all the broken pieces of stuff and putting them in large garbage bags. His nose became dull to the stink after a while, but it didn't actually make the situation better. When his dad came home he was furious, and when his mom came home she nearly threw up.

----

"Here it is," Nikki said, handing the portal device back to Mark.

It was the next day and the two of them were heading to school together. Thankfully after the one fart Nikki checked her phone and saw Mark's message. It might have been entirely too late, but she was able to close the portal before any more damage was accidentally caused.

"I probably could have farted again too," she said to him. "I thought about letting out some more in class after that first one, but I didn't want it to smell too bad around me, y'know?"

"Yeah." Mark said plainly as he put the device safely inside his bag. His tone seemed a bit upset.

"Hey..." Nikki said in a concerned voice, "I'm really sorry about what happened yesterday. I honestly meant to just play a little joke on you, and I had no idea the portal was still open after all that happened. I don't know how to fix things, but if there's anything I can do-"

"Stop." Mark interrupted. "It's... okay. You don't have to worry about it, really. It was just an accident. I told my parents I was working with some chemicals in the bathroom and accidentally went overboard. They think the... smell is just part of some science experiment gone wrong."

"Really? Are you sure?" she said.

"Yeah."

"...Phew! That's a relief! I seriously thought you were going to be mad at me there. Ah, thank god!" Nikki cheered, going back to her old self. "So what about all the damage though? Are you covered by insurance or something?"

"Probably not." Mark said flatly. "But it's alright. I figured I might sell a bit of this tech to a portal security company or something. Remember how you were worried about someone accessing your receiver without permission? They'll probably pay top dollar to know how I can hack their systems so easily. That'll be more than enough to repair the bathroom floor and replace the stuff that got broken."

"Wow, good idea!" Nikki said, legitimately impressed. "How NOBLE of you, using your powers for good instead of evil," she joked.

"I don't know about that, I mean I'm still doing it for my own benefit, aren't I?" he said back.

"Just shut up and take the compliment!" Nikki laughed.

Things seemed to be back to normal. Nikki was in a better mood since Mark assured her things were going to be okay. He could tell that she was actually worried about him yesterday too, and because of that he didn't feel any anger or resentment. The two of them continued to walk to their classes together, like nothing had ever happened.

"So..." Nikki began, "what are you going to do with the portal device now?"

"Huh?" Mark reacted.

"Well, I mean you just got it back. You probably had a lot more experiments you wanted to try out with it, right?"

She wasn't wrong. Mark still had a list of things he wanted to test but never had a chance to yet. Nikki continued.

"I'm just saying... I don't mind helping you out. Things didn't exactly go as planned yesterday, but if you want to use it with me again sometime I promise I'll be more careful."

Mark thought he was hearing things. Despite everything that happened, all the horrible disgusting ass torture he went through, Nikki still wanted to try it again. He had nearly died and had his house blown up and she was asking him this. She actually was. Mark looked at her in disbelief and she only smiled back. Today Nikki was wearing a soft cotton shirt and black leggings. The smooth dark material hugged her ample curves like a second skin, leaving next to nothing to the imagination. Mark desperately wanted to tell her no, every thought in his brain was blaring with warning sirens. But still...

"...I'll think about it." he said.