After the jump you'll find a video, the first 33 seconds of which contain the best statement ever: The early astronaut urination system used condoms, sized small, medium, and large. But sizes were renamed "large, gigantic, and humongous" when the men would all grab the larges, regardless of their true size. Magical.
According to astronaut Rusty Schweickart, in an 1976 interview with Peter Washall, ego was actually a problem for proper space peeing:
And then there's always the possibility that in maneuvering around in a suit you can end up pulling off the condom, and there's always - we have three sizes you know, small, medium and large - in diameter, and there's always this little ego thing about which one you do pick. of course the smart guy picks the right size, because it's very important. But what happens is, if you get too small a size it effectively pinches off the flow and you just turn yellow because you can't go; and if, on the other hand you've got an ego problem and you decide on a large when you should have a medium, what happens is you take your first leak and you end up with half of the urine outside the bag on you. And that's the last time you make that mistake. So it's a cute little trick there.
These guys could get through the utter insanity of astronaut training, but couldn't be honest about their penis size. Anyone else a) totally believe this and b) feel bad believing it, because it's such a stereotype?