But a itching began all over his torso. His top button on his shirt was open revealing his smooth chest - that was now growing donkey fur. It was slowly filling in his skin - human skin, not meant to grow donkey fur and the thought that he would be on all fours before he knew it woke up his instinct to run. He ran to the door but found it locked - his dick was sending orgasmic feelings to his brain despite the changes and he fell to his knees in near ecstasy and pain.
The two girls were enjoying the show immensely. This young jock, now crowned with jackass ears. They saw the bulge in his pants and knew that his cock was slowly growing inside his briefs - growing to donkey proportions. He felt a tugging there and suddenly had the urge to take his trousers off. But he couldn't! Not in front of these women! But the heat and itching grew worse and he found himself unbuckling the fly - and forcing his pants around his ankles. The relief was huge, but then he realized he had given into his animal instincts. Jack asses didn't wear clothes - and now he had no pants. Worse than that the changes that were occurring went way beyond his ears that were now as hairy as donkey ears are. His thighs were growing gray hair, and his dick had grown. It stood erect, and he tried to cover it. At the base, there was a thick fold of dark flesh which was snaking its way along his length. It was a sheath! Like all jackasses have.
"Noooo!" he cried.
He looked mournfully at his muscular smooth legs being invaded with gray hairs, and turned again to the door. As he did he gave the girls a full view of his butt - also becoming covered in hair, and the skin of his anus was dark - nearing black. His buttocks were more muscular, and above them first rudiments of a tail were budding. A small fleshy lump above his arse.
"Oh god! Help me! Help me!!!" he cried, falling to his knees in despair. Feeling totally helpless and humiliated and terrified at he same time. He could hardly even comprehend what was happening to him as he looked at the growing cock between his legs - the sheath had nearly covered the length, and it was twice its original size.