Ben felt the heat flood his body as the injection spread. Fire sprung up all through him as his entire genetic code was rewritten. The easiest change to see was the mix of white and dark hair that started to spring up across his body. He watched in a mixture of fear and interest as it grew.
This was it. This was what he'd signed up for. To be the biggest, strongest...
Suddenly his manhood began to quake and shiver. Cramps wracked his body as he watched in horror as suddenly his cock sank into his groin, sliding in with the oddest sensation he'd ever felt.
The doctor looked worried and squinted at the bottle. "Damn it! They never can figure out that XX is female and XY is male..."
He looked embarrassed at Ben, "Ummm...looks like this trip into bulldom has taken a detour...you're destined for the dairy barn for now..."