Pegged for the First Time by Slime

Mark sat in the waiting room, his leg bouncing nervously. He had an eager energy in his stomach that ran all the way down into his balls. His dick was already growing fat, pressed between his boxer briefs and his thighs.

He had seen the ad online. They were looking for testers for a brand new type of sex toy. A living gel that would respond to the user's wishes. He dismissed it at first, ready to watch a guy get fucked by a hot girl. But then Mark came back to it, the banner pointing up at the video saying, "Wish This Was You?" Yes, targeted ad, he did wish that was him. He had used dildos on himself before, but had always been too embarrassed to ask a partner to peg him. This seemed like the perfect opportunity to make his fantasy a reality.

So after a brief questionnaire about his kinks and a medical waiver, here he was. There were other people, all of them doing their own little nervous fidgets.

A doctor opened a door and called his name. He smiled at Mark in a way that made him blush.

He was led to a typical looking exam room. The kind naughty nurses emptied balls in. A metal box stood on the desk. He stepped closer to get a better look. "Hello, Mark," a voice said. "I'll be your partner today."

"Uh, hi," Mark said.

"I'll be using this to speak to you throughout our session today. You selected a preference for a feminine voice, is that correct?" The voice was coming from several different speakers in the room.

"That's right," he said.

"Very good," the voice said. The metal box clicked open and let out a small hiss. Something green and slick pushed it the rest of the way open. "This is my body," it said.

"Okay, great," he said with a small chuckle. He'd seen art online. Oozey creatures fucking people, tying them up with tentacles and milking them. It was surreal to be about to experience it for himself.

"You will answer me with 'ma'am' going forward. Understood?" the voice asked. The slime rolled over the lip of the box and cascaded down onto the floor.

"Yes," Mark said, his heart beating. The fluid collected into a long strand that snapped as it thwacked against his arm. "Yes ma'am!" he said.

"Take off your clothes," the voice said and Mark obediently kicked off his shoes and hurried to tug his socks off. "Faster!" it said and he rushed to yank his shirt off and shove his pants and underwear down to the ground. His dick bounced as his waistband passed over it, already hard. A little strand of precum stretched between his underwear and the head of his cock.

Mark's breath quickened as the goo slithered along the floor. It touched him and he was surprised to find it was warm, like candle wax. It created a tendril that snaked up his leg hairs and gently grazed the underside of his dick. He let out a long breath.

"Get on the table," the voice said. Mark hopped up and sat on the crinkly paper. The ooze snapped out and left a red welt across his thigh. "On all fours," it said.

"Yes, ma'am!" Mark said. He obeyed, flipping over, resting on his hands and knees.

"Good boy," it said. The slime shot up and landed on his back, spreading its warmth up onto his shoulders and down his spine onto his ass. The goo tangled itself in his hair and pulled his head back. "You want me to peg you, don't you, filthy slut?" it asked.

"Y-yes, ma'am!" he said, his head still craned back. The slime spread to wrap around his neck. It pushed his head down and pulled his ass up so it was spread open. It tightened around his throat as some trickled into his mouth. It tasted sweet as it traveled along his tongue. It grew wide in his mouth, causing him to gag.

"Hold it," the voice said. His eyes watered. His cock pulsed, his balls dangling between his thighs. The tendril in his mouth pulled itself thinner, allowing him to breathe. He coughed and caught his breath. The tendril went back in and gagged him once more.

The ooze trailed down between his ass cheeks and coated his hole. Mark felt himself open up under it's warm touch. The ooze in his mouth eased up again and he slobbered down onto the table.

"I want you to use me, ma'am," Mark said between heavy breaths.

"I'm going to," the voice said. He felt his asscheeks being pulled open even further. The slime pressed into the opening, running along the rim. Mark's face grew hot. He moaned and leaned back into it, wanting it to go deeper.

"Please fuck me!" he shouted. The ooze went back into his mouth and constricted his throat. He tried to cry out as the ooze inside his ass thickened and grew longer, pressing deeper into him. It allowed him to breathe as it pressed into his prostate. "Oh fuck," he said as it pushed down onto it. He felt the sensation down through the tip of his cock, which was now leaking a steady stream of precum.

The ooze pulsed, sending a thick shockwave down its length. Mark whined, balling up the paper in his fists. He started to reach down to touch his cock, desperately needing to stroke it. The goo fell down his arm and snapped around his wrist, yanking his hand back down onto the table.

"You'll cum when I tell you to," the voice said. His hole made wet noises as the slime pulled out and then pushed back in. Slowly at first, he could feel every inch as it slid into him, pressing against him inside.

Mercifully, the goo trickled down along his balls and up around his dick, forming a sleeve. It squeezed his cock, massaging the head. Mark cried out, feeling his muscles clench. The ooze sleeve started to pump his cock in rhythm with the slime dick fucking his ass.

Mark's breath caught in his chest. He felt the orgasm building up. The slime in his ass moved faster now. The sleeve squeaked and squished as it started to suck his dick. Mark felt his brain empty. All he could think about was the dick in his ass and the cum that threatened to shoot out of him at any moment.

"Cum for me, slut," the voice said. The ooze rammed against his prostate and stayed there. The sleeve sloshed along the length of his dick.

"Yes! Yes, ma'am! Yes ma'am!" he screamed, his voice high and desperate. He grunted and moaned as the building pressure finally blew. He looked between his legs. His thick dick was shooting cum into the green goo, which had stopped stroking him. Every twitch of his cock pressed against his prostate, throwing it against the dick that still filled him up.

The sleeve started to stroke him again and he cried out. Something between a laugh and a cry escaped him as his body shook. "Please, please no more, ma'am," he begged.

"I think there's a little more cum in there," the voice said. Mark gasped and laughed as the slime began to slow. His breath was heavy, but relieved, his body melted down onto the table, his muscles putty.

The slime slowly withdrew from him. He leaned up and watched it slide back into its box, his cum floating along inside it. "Thank you for joining our trial, Mark," the voice said. "Please collect your things and meet with reception to provide feedback.

Mark collected himself before he could get his clothes back on, still feeling a little lightheaded. He ran his hands along his body, down to his hole. It hadn't left any slick residue, but it was warm and delightfully sore. His cock still twitched, one last little bit of cum oozing out.

He stuffed his dick back into his underwear and got dressed. The people in the waiting room all gave him sly smiles. He heard someone else moaning off in another exam room.

Mark filled out the exit survey, rating everything the highest. Where it asked "Would you like to receive updates on further trials?" he circled yes so many times the pen almost tore through the paper.