Until last week I'd never really examined this question. I had in my head the vague notion that if you suddenly exposed a human to the vacuum of interstellar space, he'd promptly fly all to pieces. I thought we needed constant air pressure just to keep our bodies intact.
Well, it seems silly of me now, because I have been enlightened by a really good and detailed article explaining just what nasty things would happen to you if I pushed you out of the shuttlecraft, and how surprisingly long you could survive out there and even recover from your internal injuries if I deigned to rescue you:
Outer Space Exposure, by Alan Bellows.
Oh, one other silly thing I'd picked up: the use of the word "implode" for what happens to humans in space. This makes no sense because an implosion is a body collapsing on itself, which is the opposite of what you'd expect in a vacuum. But I've often heard "implode" instead of "explode", and I'm afraid I've used it that way myself.
Irrelevant but funny: