I'm sorry, Kitty, but you did kinda cross the line here. I think a lot of people are being very insensitive with the whole "lol Kent Hovind prisonrape" jokes, too, but this is about the fact that, when you said this, you did cross the line.
Besides, if men couldn't be raped, "reverse-rape" wouldn't be a fetish to begin with. (Seriously, the sheer amount of "reverse-rape" porn out there is staggering. It's a surprisingly popular fetish.) Yes, people's bodies respond in a certain way to sexual stimulation. But if their minds and bodies don't both "want it," it's rape. Period.
And to the anonymous "suck it up and be a man" asshole, get your mind around this one. When I lost my virginity, neither I nor my then-partner even really wanted it. Both of us thought the other was expecting sex, so we delivered. Afterwards, both of us admitted that it hadn't been very good, because we both felt coerced. He ejaculated--but that doesn't mean shit, as the numerous scientific links by other commenters have pointed out.
And yes, the whole relationship between me and this young man was so horribly dysfunctional, that bad sex was the least of our problems. But it still illustrates the whole "non-consensual ejaculation" thing nicely.