Every character in this story is 18+. It contains all-the-way-through penetration. Nobody is injured but that requires a little bit of suspension of disbelief.
Mr Roberts was giving a lecture on the human digestive system. His tone was dynamic, body movement, fluid. He was dropping pop-culture references relevant to today's youth left and right. Still, not a single pair of eyes or ears were on him right now. Half the class was on their phone, the other half chatting with each other. He had been teaching at this school for 25 years and saw the student body slowly degrade into a bunch of idiots and vapid sluts. Heck, the infirmary had been refurbished as an abortion clinic.
His A-game wasn't working, as usual, but today he brought his A+ game: a hands-on experiment that had everything kids these days liked.
He scouted the room for a candidate. The student that most stood out was Dakota Fischer who instead of ignoring him at her desk, was ignoring him while sitting on another student's lap. They were both playing on their phone but her nonchalant bouncing told enough of what was happening under her skirt.
"Dakota Fischer and Dylan Lawson, are you having sex in my class!?"
Some girls in class giggled, one of them gasped. Dakota, without even slowly down her coitus, gave Mr. Roberts a face of equal part sass and bitchiness and said: "O.M.G. old man, don't start rumors, it's just anal!" Dakota lifted her skirt and exposed her immaculate smooth pussy to him and a couple students who had turned around. It was indeed not being penetrated; Dylan's cock came out of his jeans and was buried inside her butthole. Mr Roberts wished he could say that was the first time he had seen the pink bead piercing her clitoris, but that girl's skirts were always so ridiculously short that her secret garden hadn't been a secret since the first day she joined his class.
Mr. Roberts pretended to be offended and partly covered his eyes to a handful of student's laughter "I don't need to see this, Miss Fischer."
The whole class was back to ignoring him. She wasn't really having sex, it was only anal... this was somehow an acceptable answer to these animals. Human civilization would surely not survive this generation, but he wasn't going to give up just yet.
"Dakota, can you tell me how long your digestive tract is?" He had JUST told them this.
The shoulder-length blonde girl in the back row was paying him no mind. Still busy bouncing her ass on a friend... or maybe just acquaintance's cock and texting.
"Dakota!?"
She gave an annoyed "tsk" before looking up.
"I dunno, this long." She used her hands to measure from her mouth to the chair.
"Don't you think it's longer than that?"
"Nope"
He lost her again.
"Dakota come up here." He had to ask 4 times before she begrudgingly got up as if being forced to leave a warm bed.
"Come on, dude, not cool," Dylan whined, tucking his penis back in his pants.
Even in school where every girl was dressed like a prostitute, most of the guys looked up from their phone to watch Dakota strut her stuff. That skirt was only a few inches long, barely covering her front and merely resting on the top half of her young juicy buttocks swaying as she made her way across the room. Her pink spagetthi strap tank top was so ill-fitted and low-cut that one of the straps slipped off of her shoulder as she walked, exposing her right breast, nipples and all. I wasn't until she reached Mr Roberts' desk that she lazily pulled it back in place. He had heard many of his male coworkers bragging about fucking this little minx and he could definitely believe it. He'd never do such a thing, of course, as he still had an albeit waning shred of integrity left.
"What?!" Dakota asked, annoyed, once she reached the front of the class, striking a slouching pose which made the precarious shoulder strap drop yet again. It was hard to look away from the exposed breast. So perky and with puffy nipples begging to be pinched... Mr Roberts shook his head to snap out of his trance. He couldn't let himself get distracted now.
"Miss Fischer, you're going to help me demonstrate how long a digestive tract really is."
"Longer than your dick!" Dylan yelled out.
Ignoring the bad attempt at emasculation, Mr. Roberts went with it.
"You're absolutely correct, Dylan, it's longer than anyone's dick."
Some guy in class shouted "not my dick" to roaring laughter. Mr Roberts was elated that his plan was working. He was getting them interested in biology.
"I dunno Mr. Evans, is your penis longer than 9 meters!?" No one reacted, he had lost them again. Even Dakota was walking back to her seat. He grabbed her arm with a bit more force than he should of, but it did make her stop in her tracks. Mr Roberts saw something in her face at that moment. Respect? Probably not. She simply appreciated being handled roughly it seemed.
He began his motivational speech: "How do we know the digestive track is that long? Experimentation! Never guess anything. Never just believe what people tell you, including me! You have to try things for yourself! Dakota can you show your anus to the class?"
Surprisingly, this request she didn't even question. With a smile, Dakota turned around, bent over enough for the little amount of fabric covering the top of her tight behind to recede upwards to her lower back then spread her cheek wide to expose the pink bleached asshole between them. Some students didn't even look up for that. Dakota's asshole was something they had all seen countless times before, most of them probably fucked it in gym class earlier today as she was known to always accidentally get the changing rooms mixed up. How that cute little hole could look so tight after being pounded all day and presumably all night was a biology experiment for another time.
While Dakota was putting on a show, Mr. Roberts moved a heavy plastic bin from under his desk to the floor next to her.
"I have here 9 meters of industrial pipe cleaner." He opened the box to reveal what looked like a long black gummy worm of about an inch and a half in diameter.
"Let's see if we're really all connected in there and how long the digestive tract is for a human of Dakota's size." Dakota wasn't really paying attention and didn't understand what was happening but she didn't even flinch when Mr Roberts inserted the tip of his long worm inside her rectum. She kept spreading her cheeks, only looking slightly less bored than a minute ago. He had marked the pipe cleaner every 50cm and the first mark was still in his hand when the worm seemed to bottom out into Dakota's colon. She winced and let go of her cheeks to brace herself against the teacher's desk but otherwise stayed put.
"Looks like no one at this school has a penis longer than 40 centimeters..." Mr. Roberts thought that was a pretty good joke. It implied everyone at school at fucked Dakota in the ass, that Mr Evan's comment from before was debunked, and it educated them on the depth of the last stage of the digestive tract, but he didn't get any reaction. He realized he should have used nches instead of centimeters but the moment was gone. Besides, he wasn't going to give up on the metric system either.
A little twist of the wrist and the pipe cleaner did it's job of curving along the path . This black rubber snake had been well lubricated but he still had to constantly stop his efforts to spread Dakota's cheeks wide with his hands to reset her anal sphincter that was being pushed up a few centimeters along with the tube. This was all for science, of course, but there was some satisfaction to be had with man-handling Dakota's ass after being teased by it for so long. After a 150 centimeters, Dakota was having issues standing straight and her soft moans were hard to read: mostly discomfort with a hint of titillation... maybe? Or was it nausea?
Push-spread-push spread, this routine took half of the class's scheduled time.
"Let's see how far we are." Mr Roberts turned Dakota around and held her upright. She looked in pain and clutching her stomach. "Let's get a better view." He examined the sad excuse for a skirt Dakota was wearing and found a small zipper that allowed it to slide right off her slender hips. He then pulled up her shirt, forcing her to raise her arms in the air instead of over her belly, which had been hiding the progress. He held her arms up as gently but as firmly as he could. Now students could see a lump zigzagging across her abdomen. "Without looking, Dakota, can you feel how far we are?" Mr Roberts let go of one of her arms and Dakota pointed with perfect accuracy at where the snake was up to.
"Very good, it should only be 2 more meters to the stomach"
"Mr. Roberts, I don't feel so good"
Mr Roberts was just amazed that she had used his name for the first time. This was definitely a step in the right direction.
"Hang in there," is all he thought to reply.
Mr. Roberts was pretty close in his estimate. 175 cm later, he felt the worm break through an opening. From Dakota's distorted body, it looked like he had reached the stomach. The wobbly naked vixen started throwing up. He predicted this reaction, which is why he had moved the garbage bin next to his desk before class. He bent the girl over his lap, her rear end facing the class and her head in the bin. He managed to convince himself that grabbing Dakota's left breast with his right hand was the best way to hold her still. It was harder to justify why he was squeezing and massaging it, though.
Now everybody was paying attention. At least through their recording phones which still counted in Mr. Robert's eyes.
"Let's see if we can find the exit, or in this case, entrance, to the esophagus. He poked around for a while, Dakota was throwing up loudly and non-stop to the delight of all students. "She'll be fine" he reassured the class, but no one had any concerns to begin with.
When Dakota's butthole started swallowing tubing more easily as he pushed, he knew he had penetrated the final sphincter and was on the final stretch through the esophagus. Having Dakota horizontal on his lap would have made it a breeze to push through the final meter, but he wanted the class to see the tip come out of her mouth. She had stopped throwing up (probably because her gullet was clogged by a thick dildo-like object) so he turned her around to give everyone a better look.
Dakota was now sitting on his lap, facing the class, her butt sticking out on the side enough for his right hand to keep jamming and twisting the almost fully-expended pipe cleaner. His left hand was holding her her head straight by the hair. In this new position, and with everyone filming and possibly live streaming, continuing to fondle her tits would have been a bad idea.
Without being prompted, Dakota opened her mouth and stuck out her tongue. She couldn't help herself, it was like she was gagging on an invisible dick. Her face was bright red from exertion of throwing up and hopefully maybe a bit of overdue embarrassment. Mr Roberts didn't see well from his angle but the exclamation of his audience and the now muffled gags of his assistant tipped him off that the worm was showing its head out of the throat. Stretching his pushing arm over her head and jamming a few fingers deep in her gaping mouth, he could definitely feel the tip of it pushing through the pharynx and into the oral cavity. Cramming more worm was harder than ever now but a few minutes of effort had the well-traveled end of the pipe cleaner clear Dakota's mouth like an alien's tongue.
Dakota was now alternating gags and screams, but her screams were barely audible. Her eyes were crossed, staring at the first phallic object she had ever wanted out of her throat.
Mr Roberts requested Dylan's presence and, this time, didn't need to ask twice. Dylan actually looked excited to participate in a school project. Truly a miracle.
"Dylan, how long is Dakota's digestive tract?"
"This long?" Dylan gestured the same ignorant assumption Dakota had made of the digestive track being only as long as upper body.
"Dylan, look." Mr. Roberts was tapping the butt end of the pipe cleaner that was clearly marked with 8m in green letters at the junction of the stretched anus.
"8... M"
"What does the M stand for, Dylan? Mmm... meeee... meeet... meters, Dylan, Jesus Christ!"
"8 meters," Dylan repeated proudly.
The whole class cheered and lifted Mr Roberts up in the air, carrying him off to the teacher's excellence awards where he cleaned house. When he snapped back to reality most of the students had left, some simply too absorbed in their phone activities that they didn't notice that class was over. Dakota was convulsing, still naked on his lap, trying to push in or pull out the full-body-violator with no success.
"Do you want me to take it out now?" Mr. Roberts asked the panicked blonde.
Dakota nodded and gave him puppy dog eyes while suppressing twitches from her painful gags and muffled coughs.
"I misjudged you, Miss Fischer. If anything, you make an excellent assistant," Mr. Roberts said while forcing the first few of many inches of rubber farther out of Dakota's mouth; it sounded easier to pull it out this way. "If you help me with experiments during every class from now on, I might even give you a passing grade. Wouldn't that be something else?"