i'd simply go into the gory details of an std - not leaving out any puss or the contagious factors.

if that didn't work, i'd tell him i'm a hermaphordite.

I don't know about the no daddy no thing. Someone attacking you is already pretty messed up in the head, that might just give them some jollies.

I shrivel and probably tuck in like an ice swimmer at the thought of rape to start with, so really I think I am less use on this topic then the girls.

If your voice doesn't shatter glass when you're under duress, proclaim that you're a man, and tell him everyone in prison will know he's a fag (be sure to use that term) when he gets caught. If you're convincing, you might get a thorough beating, but unless he got around to checking you might get away unraped. Maybe. On the other hand, rapists love guns (it goes hand in hand with the power trip), so pretty much anything you say could get you shot.

If he's unarmed, nonverbal communication would probably be your best bet. Calmly sticking a finger through his eye or ripping off an ear would probably do it. (For some reason, most people being assaulted tend to shy away from mutilation. It's like coloring outside the lines or something.)

It is kind of like when men fight. There is a plain old fight, and then there is the fight when you really know they mean it. When men go for the nuts you know it is a fight were they mean it.

actually, according to me, the aiming at the thunts doesn't work to well, but reaking a finger is really really easy and really really painful... that and the eyes are wonderbar

thunts? i'm never ever typing on my mom's computer again...
the nuts... the nuts... most guys are actually used to it by this stage of their life, and in a real fight it just makes them more angry than hurt