Jeff stripped in preparation for the changes. He glanced at his reflection in the full length mirror that was attached to his bedroom door. He felt anxious for the changes that were about to come.
After only a few moments, Jeff began to feel the effects. The changes started at his feet as they became itchy. The skin on his feet became itchy as a bluish-grey leathery hide began to replace his soft flesh. The strange sensation slowly made its way up past his ankles, and then his knees. Every bit of skin that had been transformed so far had lost its hair, the hairs had fallen out of their follicles.
Jeff watched in amazement and anticipation as the transformation crept up his thighs. As soon as the changes reached his hips, he felt a tingling sensation in his crotch that made him moan. Instinctively, he caressed his half-hard shaft with one hand while his other hand cradled his sack. Before Jeff knew it he was fully erect and slowly stroking his cock. The foreign texture that now covered his rod and sack had made him feel even more sensitive. His pre was practically dribbling from the tip, making each stroke smooth and sensual.
That's when the real changes began.
It felt like some invisible force was pumping up his penis. Soon his normally 6 inch length had swollen to 7 inches, then 8 and beyond. As it grew, it began to take a more tapered appearance, losing the classic mushroom-head of a human male's rod. His shaft seemed to grow thicker by the moment as well, becoming so thick that he needed both hands to wrap around his entire rod. Both of his hands were now stroking his shaft, bringing him closer to release. The growth slowed once his prick had reached a length of 12 inches and a girth similar to a large grapefruit.
As he pumped away at his meat, the transformation continued throughout the rest of his body. All of his skin had now become grey, smooth, tight, and leather-like. His body hair had fallen out and he was growing small spiny fins on the back of his legs and forearms. His face pushed out slightly, forming a partial muzzle, filled with razor-sharp teeth. He felt a dull ache in his back as a dorsal fin began forming, but he was too "distracted" to do anything about it.
He was nearing his climax. his muscles were getting tight all over his new form. His hands were a blur as they rushed up and down his monstrous shaft. As he got nearer and nearer he could feel his balls pulling closer to his body, and then finally going up into his abdomen. He could feel it, the point of no return. And then, he passed it. He bucked his hips in the air as ropes of his seed shot from the meat in his hands. The spasms kept coming, as did more spurts of semen. After what seemed like an eternity, his body began to relax.
As his shaft began to soften, he watched as a genital slit grew from just above his shaft to just under where his balls usually rested. His penis slowly retracted into his new slit. Once the tip had disappeared from view, he cautiously reached a finger inside. To his relief, he was still male. His family jewels were just under the surface of his new crotch.
He looked at his reflection again. A lean shark man stared back at him. To be honest, he was getting turned on again.
He felt a stirring inside of his slit. As the folds of skin began to part he saw something that took his breath away. Two tips were emerging. Instead of one cock that was as big around as a grapefruit, he soon saw two twin cocks that were each the size of a coke can.
He didn't hesitate to take one rod in each hand as he jerked himself into ecstasy.