Rock! The World Series of Roshambo
I entered the $200, winner-take-all, 64-person World Series of Roshambo tournament since I knew the optimal strategy and the whole thing was televised on ESPN. Roshambo is the game of "Rock, Paper, Scissors," and has some important elements of poker in it, namely reading your opponent and exploiting his weaknesses. The optimal strategy is to throw at random. However, like poker, better-than-average results can be achieved against players who do not use the optimal strategy if you can figure out what their next move is likely to be.
I got paired with Rick Wampler for the first round and was prepared with a seven-throw random series. However, at the last minute, they changed the first round from a single throw to best four out of seven, meaning that with ties, my seven random throws might not be enough. Rick went up on me two-nothing and three-one when I managed to climb back to even it up at three. But I was out of throws! I had thrown two rocks in a row and didn't think he'd put me on a third rock so that's what I threw. He unleashed the dreaded paper and I was on my way to ESPN for my exit interview.