All of my caps can also be found on my Deviantart at https://www.deviantart.com/caveingeek
There you will find exclusive galleries and uncensored versions of some of my captions!

Justin still didn’t know how the device worked, but he sure knew what it did. It had started a week ago when Justin had gotten the chance to tour a high-tech experimental facility. It had been a real treat. Justin loved all things tech, and he just so happened to win a contest to tour one of the biggest innovators in the space. The tour had been lots of fun and very interesting, even if he wasn’t entirely sure what some of the new inventions they were cooking up were. Roughly halfway through the tour, while passing by some storage shelving, Justin had swiped one of the experimental products off the shelf and pocketed it. 

It wasn't until he got home that he had time to look at it. The device wasn’t something he had expected it to be. While stealing it, he really hadn’t gotten to study it at all, but now that he was staring at it, he could see that it pretty clearly resembled a butt plug. It had a pink base that surrounded a convincing enough-looking gem. The really interesting part was the bulb portion though. It had lines that crisscrossed the surface like some kind of elaborate circuit board. When he touched the gem at the base, the plug vibrated slightly, and the lines gave off a faint glow.

Justin had never really been one to try butt stuff, but having an experimental product like this meant he could be among the first to try it. He figured trying it once couldn't be so bad. If he didn’t like it, he would just pull it out and throw it away. Justin stripped down naked, throwing his clothes on the floor of his bedroom. Not really being prepared for this endeavor, he didn’t have any lube on hand. Justin instead opted to use a bit of Vaseline to help ease the plug in. Once the bulb had been lubed, he began to slide it into his ass. It was surprisingly easy to do, as the plug itself was not all that big. So far so good, he thought.

Next was the part he was unsure about. The vibration function would probably feel somewhat strange. Nervously, he tapped the gem. Much as before, the plug vibrated slightly, startling Justin a bit. Then it stopped. Maybe the device was defective, he thought. Surely it was supposed to vibrate longer than that. It was around this time that the plug started to expand inside of him. The sensation was sudden and, to Justin’s surprise, pretty pleasurable. He could feel it growing larger and larger inside of him. A bead of sweat began to form on his brow as he realized he wasn’t sure how big it would get. It grew and grew, smashing against his prostate and causing his cock to leak clear fluid. Just when Justin was about to panic, it stopped. That was close to injuring me, he thought as the now incredibly large plug took up nearly the entirety of his colon.

Then the plug began to vibrate again. It pulsed rhythmically, massaging Justin’s prostate. With each pulse, Justin began to feel an odd sensation. Was he beginning to feel heavier? Justin grabbed his ass cheeks and held them. With each pulse, the skin seemed to expand in his hands. He should have been panicked, but it felt too good. The swelling sensation, combined with the prostate massage, brought him to the edge of orgasm. The swelling spread further, going next to his chest, where it started to build mounds of flesh under his stiffened nipples. Each pulse felt more and more intense as more effects took hold. His hands became slender and more dainty. His hair grew a quarter of an inch with each pulse. At last, he could take it no more and came. What shot from the tip of his cock was not cum though, but a mostly clear fluid. His cock became limp and began to shrink in time with the pulses. Justin scarcely had time to react before another orgasm began to build.

It was roughly an hour before the Device finished whatever it was programmed to do. Justin had become a fat-assed, busty brunette with a lust for cock. Justin had assumed that the device would shrink back down after it was done so that it could be removed, but this was proving not to be the case. The device was still far too large to pull out, and it pressed against her insides with any move she made. Perhaps the device really was defective, and the shrinking back down was the only thing missing from the product. Whatever the case may be, Justin needed somebody to come over and pleasure her. Her libido was through the roof, and her newly formed pussy was drooling with anticipation. She just had to make sure nobody accidentally turned the device on again…