Presidential debates are often a high-stakes poker game where bold risk taking and body language can matter more than the policy cards each player holds. The losers find out--often too late--that their gaffe or mindless gesture was a turning point in the campaign. That's not lost on President Barack Obama and Republican nominee Mitt Romney who likely know that debates are easier lost than won. Some of the most famous slips have become defining moments in a candidate's career. Remember these?