From his seated position, Jeff could see how thick and muscular his legs had become. Inhumanely thick and capped with shiny black hooves. Hairy too. His legs' hair had grown in quite thick and extended well up to his stomach and chest. His penis was thicker and longer and very human looking... though far to large for it to be an ordinary man's. Jeff reached out to touch it and noticed that his enlarged arms were becoming very hairy like his legs.
"What the heck?" said Jeff. "I asked for just my lower body to change. What's going on with my arms?"
As Jeff looked over his bulging, muscular arms and swelling upper body, he noticed the pinky finger on his right hand was half its size. As he watched, it shrank into his hand and vanished while his thumb started to lengthen. While watching this new change, Jeff noticed his arms seemed longer than before so he held them out to check. His arms *were* longer and he had lost both of his pinkies!
While he held out both his arms, he watched as his thumb and remaining three fingers began to fuse and form two thicker fingers... which changed more and become black shiny hooves like his feet. Looking down, he saw his balls had become larger and were resting on the floor while his penis was even longer, thicker, near jet black and reaching across his stomach. Horrified, he tried to stand up but just sort of twisted on the floor and ended up crouched on all fours.
This felt very natural to him so he stood up. His thick arms were supporting his enlarged upper body while his back legs and hooves were supporting his enlarged lower body. He twisted his arm and looked at his chest and belly and saw, from this angle, that his chest looked odd. He took a deep breath and saw his chest change even more, from that of a muscular man to a muscular bull! Looking down, his penis twitched as he watched and attached itself to his stomach. And it continued to grow! Behind it were two large balls, which were now hairless and hanging low. Their tug along his back made his tail twitch with pleasure.
His neck hurting from watching himself, Jeff stopped staring at his navel and straightened up. Very far up. His neck seemed very long and tingling. Jeff tried to walk but had trouble since he had more than doubled in weight and his arms and legs had changed length. As he tried to figure it the changes, he straightened himself by instinctively putting his arms against the wall.
"Arms?" said Jeff? "They turned into legs! How do I have arms?"
Jeff stopped trying to walk and looked himself over. From the waist up, his body was much like it was before he clicked the "Submit" button. Below his waist, he looked like a bull. He had become a bulltaur! He asked for his lower body to be 90% bull and it now was. Jeff twisted and turned his upper body to look his new lower body over, trying to see what was 10% human about it. He could not see his new penis but he felt it hanging from his stomach. His balls felt huge between his legs. Those definitely were not human either. Shuffling his rear legs from side to side, he felt his balls move left to right in a nice slow tugging motion.
He felt very horny, trying to think of how he could satisfy himself since he could not quite reach the new parts of him with his arms. He took a few steps and found himself walking steadily now that the change was finished. He seemed to be at home in his new body.