Heh...
In my freshman year in college my girlfriend came to visit and we had a couple of drinks with a bunch of my friends in the dorm room. Well, the alcohol started to go to her head, and she kept making more and more suggestive looks and comments toward me until my roommate (bless his heart) finally took the hint and moved the party down the hall to give us some time alone. Well, right before we start going at she says "Oh, I'm on my period, is that ok?" At that point I couldn't care less. It was an interesting experience... very slippery, which was good, although the alcohol might have helped a bit as well. Er, not alcohol in her ******. In general. Ahem.
But when we were done I looked down at myself (she had been on top) and my first drunken thought was "Holy **** it looks like a deer was just gutted across my lap." Blood ALL over my thighs, and not a little. I was glistening red. My hair had turned red. I was Irish below the hips (again, not due to the alcohol).
I gingerly (heh... red hair... ginger...) wrapped a towel around myself, made a run for it to the bathroom, and scrubbed myself. When I was good and clean and didn't look like a slaughterhouse, I redressed while my girl was in the girl's room shower and went back down the hall to rejoin the rest of my friends.
"How did it go?" They asked, all grinning as I walked in the room.
I thought for a second, shuddered, and said "Beware the Red Baron."
There were a lot of groans and quite a few "EWWWWWW!"s. Overall it wasn't a bad time at all, just a lousy cleanup. I've done it once or twice since then too, and again, never a big probelm... but it was never as messy as the first time.