Jeff decided that he wasn't quite ready to include someone else in this transformation just yet, so when the list of possible targets came up and he noticed that he was included in it, it seemed logical to choose that. After a moment's thought, he also decided that the most exciting body part to try out being would have to be the cock. Blushing and excited, he quickly scanned through the rest of the options, ensuring he chose the ones that would make him aware, and being extra-careful to only set the duration of the change for an hour. He didn't want to be stuck as a cock for too long, after all. Once he was satisfied with his changes, he pressed execute with only a hint of trepidation.
At first, nothing seemed to happen. But after a few more moments, Jeff felt a lurch in his crotch, and an intense throbbing that was extremely uncomfortable in his pants. Desperately, he fumbled with his jeans, unbuttoning and removing them before kicking them away and tearing down his bulging underwear. To his surprise and confusion, his dick had grown and thickened massively, and the shape had changed, his cock head oddly swollen and bulges forming in his shaft. He found himself feeling flushed and sweaty, panting as pangs of strange sensation throbbed through his upper body. With trembling, swollen fingers, he grabbed onto his oversized cock, rubbing and touching it instinctively, arousal pumping through his head. However, none of the familiar pleasure he would have expected came when he did so, and instead he found himself giving up on his cock and rubbing his chest instead. That felt wonderful - his chest and skin was so tender and sensitive, and every touch was blissful.
A salty flavour built up in his mouth, and he found himself drooling clear, thick goo, so entranced by the sensation that he leaned back on his bed, closing his eyes and just rubbing his chest up and down with arms that were slowly shrinking and dwindling even as his torso become rounder and more shaft-like. He didn't see as his growing cock bulged and swelled more, the cock head bending down to look at him, the slit twisting horizontal and forming eyes and a nose above it. As Jeff's hair fell out in clumps, his face becoming red and swollen, his cock head started to grow more pale, the shape becoming a familiar copy of his own appearance. Hair grew bit by bit over his cock's head, soon a copy of his own haircut. Jeff's torso began to shrink, his massive cock's bulging shaft now developing arms from the bulges, the ends of which split and formed fingers and hands. Definition formed on his shaft, the shape of muscles and bones, even as his torso became soft but firm, throbbing and twitching.
Soon, Jeff's hands had shrunk down too small for him to bend them back and stroke himself, and he opened his eyes, twitching and trying to reach to gain more of the pleasue that was making it so hard to think straight. His head had pressed down into his torso, skin pushing up from his chest around his neck in a fleshy turtleneck, and his nose had flattened and vanished, leaving only his drooling mouth and eyes on his dome-like red head. As his arms and hands vanished completely, he looked up at what at first seemed to be a strange mirror, for his own head and chest was looming over him. There was a strange, twisting, cracking shift in Jeff's lower body, his legs and crotch turning around, causing Jeff to be raised up as he found himself sitting on his own ballsack, having gone from lying on his bed with his legs dangling over the edge and his cock in the air, to standing over his bed with his cock and balls resting on the edge. Except Jeff was the cock!