You always hear about some white wife being turned out by some big black dick. What if some rich white couple decided to force some young black man into becoming a mindless bull who is used at their parties?
That certainly is an interesting twist to the swinging/"BBC" parties/etc. I have a dear friend who is a major he slut (but of his own free will) and who was a precious commodity to parties since he's a well hung, sexy black man. He's always been just as coveted as the "single bi female" at parties.
Do you see a young college student perhaps getting into the scene for money (hey, college is expensive and everyone has their whore price )...? Or...?
That could be a scenario. But what I'm thinking of is far more forceful than that. The situation that puts him into the process of becoming a bull has to be something that left him no other choice but to turn into a walking sex toy.