This happened to me and 2 friends recently while playing Bad Company 2. The opposite team was one big clan, and they had 4 guys more then we did, so we asked them to even out the odds a little, because our team had massive problems defending in rush mode.
They said no. The reason? My friend was lvl 30, so we should have no problem. For your information, you need only like 6 levels to max out a class in that game, and all in their clan was around lvl 8 or so. Not that levels really matter in that game, being killed by an AK47 is as easy as being killed by an M16.
Anyways, we basically went into Gandalf mode, saying "YOU WILL NOT PASS!!!". After the most hectic 15 minutes I've had in an FPS, defending a house with increasing number of destroyed walls in it, we won.
And then the whole clan left, being beaten by just 3 pissed off guys with 8 years of teamwork behind them, and one of the worst teams I've ever played with.
It was some kind of flow-inducing cold rage, it just made us focus more. And by the gods, did we mock them when they, just before all of them had left and their team was about 4 guys less then us, asked us to even the odds...