Just one, earlier in this thread. I think it was @Sadras who mentioned male-on-male rape happening to one of his characters because the DM thought it was funny.
Edit: I will say that I don't recall if @Sadras said the DM just said that it happened to his character or if the DM tried to make him RP it (as happened in my case).
Edit#2: It was actually [MENTION=31754]Lord Twig[/MENTION], you can find it here.
Heh. i think my point still stands.