You were with a group of friends and the energy just kept building — louder, sillier, more daring. One person did something, then the next topped it, and you all got swept up in it. By the end, the group had done something none of you would have done alone: been too loud, too wild, maybe broken a rule or hurt someone's feelings. On your own, you'd never have gone that far. But in the group, swept along by the rising energy, you didn't even notice the line until you were well past it.