You lived your life as a man of science. The world was such a great big and wonderful place, but your studies focused on what you found to be the most fascinating of all: the human body. How do we work? What keeps us alive? Your research always focused on the very core of what makes our bodies tick, no matter how small. Over the past few years your focus has shifted to the incredible world of the digestive system. The fact that we can eat and process food so normally and use it to absorb nutrients was marvelous. It might even be the key to extending the human life span!

After years of hard work you created a machine that could help you experience the wonders of the digestive system first hand. You kept it in your lab, a large generator box that had the power to shrink you down to a microscopic size and teleport you anywhere. With this, you could explore the inside of another person and witness their intestines first hand. The machine had a remote, one that fit into your hand, and was designed to shrink with you. That way, once you were done collecting data, you could return to normal size and teleport back out.

You had tested the machine multiple times. It worked (flawlessly you were proud to admit) but you hadn't tested its purpose of shrinking inside another person. You needed a test subject. Contemplating where to go from here, you went to the kitchen to have some lunch. Quietly you ate a sandwich alone, thinking to yourself. Suddenly the front door swung open.

"I'm hoooome~! Oh! Hey dad!"

Your daughter Sarah had just arrived, back from a hot day outside with her friend. She had straight brown hair that fell just past her shoulders. Compared to most girls her age she was fairly short, but very cheerful. Like most days, today she was out on a jog with her friend, to help lose some weight. See, Sarah loved to eat, a LOT. You had no idea how she packed that much food in her petite body. To her, everything was tasty and delicious and she would gulp entire meals down at an amazing speed. As a result, she had started to gain weight. She wasn't fat, but she was starting to get a little pudgy. Hence, the jogging.

Sarah walked inside in her usual jogging attire. She had a tight stretchy workout shirt that wrapped itself around her ample chest. Her boobs squeezed into the fabric, pressing together. No doubt she would have people staring at them bounce as she ran. Below she was wearing her usual spats, elastic black shorts to stuck to her skin like glue. They ran all the way up her ass crack, highlighting the sheer roundness and size of her butt. Most of Sarah's weight collected at her backside, giving her a juicy bubble butt that stuck out as she walked around. Most guys would go crazy for an ass like that, but as her father you didn't look at her like that. She came into the kitchen, soaked in sweat, dripping onto the ceramic floor.

"How was the jog?" you asked.

"Jamie and I found a Mexican food truck on the way back home, I got three helpings for lunch, hee hee!" Sarah beamed.

Of course, if she had a chance encounter with some food, she was destined to eat it. As long as she was working out to get the weight off, it was fine you guess. The real problem was that she had Mexican food. Sarah was notoriously gassy around the house, and whenever she ate Mexican food she was sure to clear out the room. It made her extra gassy, it was kind of amazing that a girl that small could let out such huge smells.

You thought about it for a moment. Her ass, the way it belted out those kind of farts. It was a mystery how it worked, and that sparked your curiosity. What if you could explore inside her bowels, find out how her gas operated first-hand? It would smell awful, but after living with her for so long you thought you were just about used to it. Your scientist's curiosity started to take hold of you. Looking back at Sarah, she was bent over in front of the fridge, getting a bottle of water to rehydrate. You stared at her ass, thinking about what it would be like inside, with her bubbling bowels.

Suddenly a rather large toot shot out her bum.

"Oops! Sorry Dad."

You could hear the wet sound of her sweaty cheeks slapping together. The smell of the gas wafted over to you, it stunk as much as ever. You covered your nose, it was rotten all right. Would you really be able to tolerate that much stink from the inside? No, as a man of research, you had to take this chance. The data would be invaluable. You stood up from your chair.

"Sarah, do you have to use the washroom?"

"Huh? No Dad I'm fine."

That was good. If she felt like she didn't have to go it probably meant hear bowels were empty.

"Okay, I'm going to use the one upstairs." you said, and walked off.

You locked the bathroom door behind you. Your mind was made up, you were going to do this. Of course, Sarah couldn't know. On one hand she would probably never agree to it, and on the other if she knew about your intrusion it might cause her rectum to act differently. For the sake of collecting data, you needed to to make this experience as normal as possible. You sat down on the toilet, fully clothed, holding the shrinking remote out in your hands. The machine in your lab was already running, it would just take one press of a button to shrink yourself. Was this really a good idea? As a man of science, you couldn't stop now. You thought of your daughter's smiling face one last time before pressing the button.

----

Sarah had gone upstairs to her bedroom to relax. With her heartbeat starting to calm down, she sat at her computer, still dripping with sweat. She didn't feel like showering right now, and instead loaded up some YouTube videos to watch. Leaning back, she let out a comfortable sigh, giving her muscles some well deserved time off. She had no idea that her dad had just transferred locations, and was now inside her butt.

You blipped into existence, deep inside her body. The first thing you noticed was the heat. It was oppressive, like the kind of stuffy heat the would fill a house in the summer when there was no air conditioning. Sarah's organic walls were emanating waves of it, and the immediate change in temperature took you aback. The human body was 98.6 degrees Fahrenheit, or 37 degrees Celsius, but since she was just running outside it had to be even warmer than that. It was a muggy furnace, and it immediately sapped your energy.

The second thing you noticed was the darkness. Being inside her bowels you knew no outside light could reach you, so you were effectively blinded. Luckily you brought with you a special pair of goggles, ones that shone two flashlight beams to wherever you were looking. You reached into your pocket to get them and that was when you took your first breath.

Right away the rancid smell of Sarah's bowels attacked your body. Her ass smelled absolutely horrible from the inside! You clutched your hands over your mouth, resisting the urge to vomit. This wasn't anything like you imagined. Just smelling her fart from earlier was gross, but this was so bad it was like you had put your mouth up to her asshole and sucked it straight from the source. Her pungent odor made your nose twinge in disgust. Every breath following that one was just as bad, you were truly in another world. You coughed and coughed, collecting yourself and putting on your goggles. It was something you'd have to get used to if you were going to experience her gas later on.

The goggles flicked on, shining a bright white light inside Sarah's ass. Then you could see in great detail how her bowels looked. The walls were meaty and red, dripping wet with intestinal juices. That was good, it meant that she was healthy. The surface was uneven, crumpled up, in big fleshy ripples that writhed around in strange slow motions. You could hear gurgles up above as her small intestines worked through her meal, the amazing sounds of the human body digesting. If you looked closely at her walls you could even see veins on some of the smoother parts, weird red branching lines that made the whole place seem alien. No one had ever seen such a unique sight before first-hand. You had to be the very first!

Unfortunately, the smell was something that you doubted anyone would be able to put up with either. The cost of entering this girls ass was very steep, but you were gradually becoming accustomed to her stench. What was incredible though, was the sheer size of her rectum compared to you. Her ass was like a massive cavern of dripping filth, and it was so wide it seemed like the the ceiling was at least ten stories high. It was amazing, how big the tube of flesh had become. You could have shrunken yourself to be larger, but then she might have noticed your presence.

You began to walk around her ass, surveying how her guts functioned when not in use. You typed in notes on the screen of your remote, doubling its use as a notepad for recording data. Every detail of this excursion needed to be recorded, so that you could review over it later. The slight twitches of her muscles, the amount of gunk lining her walls, even the bubbling sounds from deeper inside that were starting to become more rambunctious, you needed to write down all of it. The anal hallway shook slightly, as a loud grumble resonated from above. You should have taken that as a warning, but you were too busy with other things.

Meanwhile Sarah was enjoying videos in her chair, having a fun time. Her guts growled and she felt herself become a bit bloated, probably due to all the Mexican food. She leaned to one side, lifting her leg to let it come out naturally...

From parts unseen her anus puckered, and then a roaring fart blew through her bowels. Loud couldn't even begin to describe how ear-splitting the sound was. It wasn't so much that you heard it, your hearing moreso became obsolete in the face of such an eruption. The booming guttural explosion resonated off her bowels walls, your ears couldn't take it, and everything became static noise. The force of her anal winds was like a tornado, searing hot and with enough push to it that it knocked you off your feet. You fell onto the mucky floor, which you noticed was undulating. Sarah's rectum was pumping out her gas, actively throbbing the hot fart through her sputtering asshole.

From the arrival of her gas came a new wave of muggy heat, making her earlier atmosphere seem like a cool breeze. Moisture stuck to your skin, bathing you in the stickiness of her fart, as the blasting winds threw more potent smell your way. It was incredible, such a natural body function, and it was able to overwhelm you so easily. Your daughter's farts were not something to be messed with, and at your new size they were more powerful than you could have dreamed. Eventually the gas blast tapered off, leaving you in the foul remnants of her stink.

Her rotten odor entered your lungs, and your body immediately started to convulse. The stench was a hundred times more concentrated than before, just breathing it burned your organs from the inside. It smelled absolutely rancid, you coughed and choked but the heavy smell wouldn't go away. Sure enough you threw up, leaving your sandwich from earlier inside your daughter's ass. It was just too much. Her farts were toxic and steaming hot, just one of them was enough to make your eyes water, even through the goggles. The air felt heavy, like you were physically being weighed down by her gas. It was hard just to stand up, and every new breath of thick air made you dizzy.

Without warning her ass fired off again, blasting you head-on with a second wave of flatulence. You tumbled over pathetically, splashing into a wet puddle of anal juices. Mucus clogged your nose and ears, and you had to wipe the sticky substance off your goggles. In an effort to escape the fart, you crawled on your belly, sinking deep into the muddy mess looking for a safe space. You took cover behind a lump of red flesh, one ridge of many lining the hot slippery tunnel. The gigantic muscles contorted erratically, throbbing as bubble after bubble of moist stink blasted through. Your small indentation of cover shifted upwards, her bowels churned, and threw you into the storm of gas once more.

After several hellish seconds, the fart was finished, and you slumped over on your back. The wafting scent of Sarah's Mexican meal hit you like a brick, and your mind became even more foggy. At normal size her spicy farts were already unbearable, but now shrunken to micro proportions they were akin to a natural disaster. This incredible volume and potency to her gas... something this big could evacuate cities. Not to mention the force behind her gaseous release, those sharp powerful winds could knock down trees. You gasped for oxygen, the odor inside her ass was so thick you cold practically chew through it. Just when you thought you had a moment of respite a loud groaning echoed from above. Your stomach dropped as her colon widened...

Sarah moaned as a third fart ripped through her ass. Mexican food always tasted so good, but when it came out it was always so boisterous. She didn't dislike it though, having so much pressure get expelled from her body at once felt good, in a way. The fart rippled through her ass cheeks, splashing the bottom of her spats with leftover butt sweat. It made a harsh slapping sound as it came out, akin to a lawnmower starting up. She giggled.

"Oh wow, I so gassy today!"

Her innards gurgled, announcing more was on its way. Sarah felt the huge bubbles inside her travel down south. It was far from over, and the next one was going to be BIG.

You hacked up a wad of filth, choking inside the humid cloud of your daughter's stench. After that third enormous fart you understood. Sarah's gas was extraordinarily powerful, practically godlike at your puny size. Her ass was capable of summoning hurricanes, volcanic eruptions of odor so strong they could bend metal. She had no idea what she was doing, by simply farting she was putting her father through torture of titanic proportions. Full of steam, the ass croaked and trembled, filling you with a sense of dread. This wasn't a place meant for someone like you to survive in. You were too tiny, too vulnerable against the might of her giant farts. You should have known better than to try to explore her bowels after a big meal of Mexican food.

Research be damned, you had taken enough brutal punishment to last a lifetime. Your lungs felt like they were failing and your vision had weary sparks from a lack of oxygen. You started to put in the coordinates into your remote to leave but it wasn't working. The touch screen was too wet and slimy with anal juices, and your fingers weren't registering properly. A low groan boomed from deeper within the darkness, causing the entire chamber to shudder. It sounded like a gigantic crashing waterfall was rounding the corner of her bowels, and by the time you spun around it was already upon you.

A massive storm of farts tore through the giant teen's ass, blasting out hot unimaginable whirlwinds. Huge beefy explosions rocked you, one after another, in a chain of sweltering gusts. Sarah sighed contently as the storm of farts sputtered past her asshole, unaware of her father drowning in the eye of the storm. You tried to hold yourself back from the harsh winds, slowly crawl into somewhere safe again, but the severe force of her gas pushed you back into a spiraling flip. The remote was torn from your hands and sent flying to places unknown. Hot flecks of filth, and giant globs of juices flew by with you, blowing through her roaring cavern. They were the size of vehicles, and splattering all over the walls of her bellowing poop chute. You hit the gummy ground with a soft thud, thrown several meters from where you started. The next thing you knew, a glob of ass mucus was being thrown overhead and landed right on top of you.

Your shoulders and head were free of the chunk of slime, but the rest of your lower body was trapped. You struggled and squirmed but your tiny limbs were too weak to break free of the sticky bonds of this sludge. It was useless, you were trapped, tied down to the girls massive bowel walls as she farted. Her chain of farts was unending, the bottom of her panties must be damp with the same sort of juices that were coating you right now. You laid there, slowly suffocating in the gas of your own daughter. The awful smell, something you didn't think could possibly get worse than it already was, had escalated to ungodly levels. Your daughter's gas was so putrid and thick that it was clogging your lungs, making you unable to breathe. Your goggles had either been knocked off or your vision had gone completely dark.

As your mind started to slip, all you could think about was how truly insignificant you were compared to her farts. They were all-powerful, bigger and louder than you ever thought possible. You were going to die a speck in your daughter's bowels, the life suffocated from your helpless body because she had to fart. The sheer strength of her toxic stench, the gas you had taken for granted, now it was going to take your life. The storm of gas filled rumbled all around you, growing more distant as you shut down, becoming a soft lullaby that put you to sleep forever.

----

A few minutes later Sarah finally felt empty. The thunderous chain of farts had ended, and left her surrounded in a cloud of her own stink. She leaned back in her computer chair and inhaled it, the rotten odor that would have caused anyone else to cry, just made her own nose wrinkle a little.

"Phew that's ripe. ...Still, it's not as bad as that OTHER time." she said, thinking back to an especially big meal she had at Thanksgiving.