What do marathon runners do when they have to pee?

[tonypaladino]

I live by the six mile mark in the NYC marathon, and there is a station of porto-potties set up and a vacant lot nearby is always full of peeing runners. So I guess they just stop and pee. I imagine the guys who actually have a chance of winning don't stop. They are sweating so much they can probably just pee in their pants and no one would notice.