I had QQ 2x in a tourney yesterday. The first time a guy I had seen go all-in a bunch of times with junk shoved in front of me. A smallish stack shoved after him, and I couldn't fold, so I shoved, too. Turned out to be the right decision; they both had crap, and my QQ held up.
About 1/2 hour later the same thing happened. Unfortunately, when the cards were turned up one guy had AK, and he hit a K on the river.