I've done this before, on alot of occasions. Mostly because I was drunk. But this time that was not an excuse, just sheer stupidity.
So I was getting out of my friend's car, they gave me a ride home, and one of my friend's sticks her hand out the window to wave bye. Me being the idiot that I am, thought it was some notion to shake her hand. So I grab her hand, just as they're driving off, and she looks at me dumb, so I take my hand away and they drive off.
Real smooth.