Such an average day had turned into a dream come true. Never in his wildest dreams did Mark think he'd get to have his crush Sarah sitting on top of him and blasting him with her giant farts. The strong stinky aroma permeated through her leggings and stung his nose. It was rank and eggy, but Mark wouldn't have wanted it any other way.

The grossness only added to his delight, something about a girl as petite and cute as Sarah blasting out wretched farts was sexy to him. On the outside she was so sweet and kind, but now he was getting to see how she really acted when no one was there to judge her. The distant giggle he heard up above after her last rumbling release of gas was also pretty hot. She was a playful farter, even though she would normally hide it, she clearly found it amusing to break wind with her tight sexy ass.

Mark huffed deeply, inhaling her scent. Sharp sulfurous gas filled his lungs and fueled his excitement. This was so amazing, he wished he had done something like this ages ago. If he had known that the sociable Sarah let out farts like these in her private time he'd spend night and day under her ass. Living between her perfect butt cheeks as she squeezed out her gas daily, it sounded like heaven.

There was only so much time left for lunch however. Soon she would get off this chair and return to class, leaving him and an ass-shaped imprint on the seat cushion. Mark didn't want it to be over so soon. School be damned, he wanted to stay inside Sarah's smelly ass crack!

There was one thing he could do. In the stuffy darkness Mark felt the material of Sarah's leggings. Underneath that was her panties, and underneath that was her... He drooled a little just imagining it. Judging from the feeling of the boisterous winds from before, Sarah's anus had to be sitting directly above him. If he could slip into her underwear, not only could he stick around with her all day, but he could be stuck directly against her erotic asshole as well!

Mark's face was red with excitement just thinking about it. Was this okay to do? Being sat on by her was one thing, that was an accident. Same thing when she farted on him. Slipping inside her clothes and touching her butthole was a whole other level. He only knew Sarah as a friend. They weren't that close, even though they were getting along well earlier. Without her consent it would be a pretty bad thing to do. The counter-argument however was wafting all around him. Sarah's farts smelled intoxicating, and her giant puckered anus was waiting right in front of him. Mark only had the opportunity to live out his fantasies now, he'd never get a chance to do this again for the rest of his life.

"Better to beg for forgiveness than ask for permission." he said to himself.

Fishing into his pocket, Mark pulled out the portal device. He needed to be careful about how he did this. Basically he was going to make a Mark-sized portal inside the leggings above him and another one the same size inside Sarah's underwear. For him it would be a gateway passing through the material of her leggings and panties. Accuracy was extremely important, he didn't want to accidentally cut through her clothes or make a portal inside her anus. The fabric wasn't sticking directly against her hole so there was a little bit of wiggle room to work with, but if anything was in the way he could become stuck when he closed the portals. That would be really bad.

With focused precision Mark aimed the portal. Sweat ran down his brow, this needed to be perfect. When he felt like he had it right he hit the button and activated the device. Both portals opened simultaneously creating the gateway in front of him. Dull light illuminated the inside of Sarah's panties from outside and he could see the faint shape of her massive asshole. It was as big as him, no, even bigger, and it looked delicious. Mark had to act fast, before Sarah felt the cool outside air touching her anus. He climbed straight up, through the portal and out the other side into her panties. The giant poophole was staring him in the face, but he had to make sure he was 100% out of the portal. He couldn't allow even a finger to be inside it when he closed the gate, and since the portal was under him it was proving difficult. Planting his hands and feet outside the whirling gateway Mark arched his back to make sure he wasn't touching it. His face and torso were inches away from Sarah's pucker, he could feel the heat emanating off of it. Ready, he pressed the button on the device with his fingers turning off the portal. The gate snapped shut, leaving Mark inside Sarah's underwear just as he planned.

Only a little part of the back of his shirt was snipped off when he closed the portals, but that could be sewed later. All things considered it was success, he had invaded his cute classmate's panties. Though faint in the darkness, Mark's eyes started to adjust to the stuffy confines of Sarah's ass crack. Directly in front of him was her anus, imposing and giant. The smell of her latent farts was all the stronger now that he was right next to the source, he took another deep breath to taste it. It had only been about ten minutes or so but he was starting to get used to her brand. As much as it was his fetish, gas was gas, and always carried a sense of repulsiveness when first being introduced. Now he was becoming accustomed to her stink, and his brain was feeling less put off by it.

The gigantic anus sat in front of him. Mark couldn't hold himself back any longer, he had to touch it. He reached out with his hands and groped the round wrinkles of flesh. They were firm but also somewhat soft. Sarah's hole was covered in a sort of oily substance, remnants of sweat and moisture from her farts as well as the other stuff that passed through her hole. Thankfully she kept herself clean as a whistle, but there was no of way avoiding having natural oils seep out of her youthful body. Mark dug his fingers deeper, sliding them across the supple skin and between the divots of her orifice. The folds of her anus were shut tight, but also home to even more caked-in sweat and oil. Hot nectar oozed between Mark's fingers while he felt around the girl's wrinkles. Is it wrong that he wanted to taste it?

Currently this was the sexiest thing he had ever done in his life. He was kneading through his crush's anus like it was a giant mass of dough, even though it was the filthiest part of her body. The smell of her gas was heavenly and the warmth of her panties made it seem like he was resting under a big cushiony blanket. Mark's dick was at full mast, twitching inside of his pants. He wanted to taste Sarah's ass. Drunk with lust he leaned his head forward, slowly closing in on the massive sphincter. He opened his mouth and stuck out his tongue, aiming the pink muscle at the center of Sarah's gorgeous hole. He was so enraptured with her ass that he didn't notice the school bell ringing in the distance, just moments prior.

Sarah on the other hand, heard the bell. She looked up from her book at the clock and noticed that lunch time was over.

"Dang, I was just getting to the good part in this book too!" she thought to herself.

She had to put back the book and get going. The thing was, she still felt a bloated pressure inside her guts. Before she went back to class she should probably let it out here. Wiggling her cheeks Sarah spread her perfectly shaped booty into the chair. She then pushed, easing the gas along until it came spewing out her hole. This fart was pretty big compared to the last couple, thankfully the padded seat absorbed the noise well. The teen let out a sigh and smiled, satisfied to let the rest of her gas out.

"Ahhh, much better..."

Down inside her panties Mark was just about to lick her butthole when suddenly everything started to shift. Sarah's colossal butt cheeks moved from side to side, spreading into the seat. Not just his tongue, but his entire mouth and head were planted into the middle of her greasey hole. He heard a distant rumbling, the rolling sound of her colon forcing through tightly packed bubbles of pressure. He was in shock, Sarah's asshole was about to fart directly on his head! This was going to be incredible, he wasn't mentally prepared. The giant bands of skin puckered against his tongue as she pushed with her muscles, scraping her oily flesh into his taste buds. The rumbling got louder and more intense, was it supposed to be shaking so much? Without warning the anal gateway split opened and blasted Mark with her gas.

It was like the worlds biggest hairdryer was turned on in front of his face, and set on high. Blazing hot gusts of winds blew out her sputtering asshole, bathing Mark in a torrent of gas. The smell was even more potent than before, since now he was drinking it straight from the source. Sarah's mighty anus contorted as she forced out her fart, battering its massive wrinkles against Mark's face. It was a bit violent, but he didn't care. The joyful experience of the girl of his dreams farting on him far outweighed the discomfort. Her fart roared through her panties and leggings into the chair. To the outside world it was silent but for Mark he was in the epicenter of a giant guttural explosion. Booming wet shockwaves bounced off the inner walls of Sarah's overhead cavern, as her anus trumpeted its puckered wrinkles against Mark's skull.

The sheer amount of stinky gas was making him feel dizzy. Noxious fumes had far past filled his lungs and his face felt like it had a sunburn. Sarah's anus pushed out and widened slightly, to let an even greater volume of gas escape, but before it could produce any more it closed back up. She was all out of farts for now, and ready to go back to class. Mark was caught in a euphoric daze, completely stunned from what happened. This girl, her ass, this smell, the thoughts that ran through his mind were all a blur.

Suddenly her ass cheeks came crashing down on him from either side, she was standing up now. It was time to go.