In the episode Phoebe gives Monica and Chandler a Miss Pac-Man game as a wedding present. At first Chandler sucks at it, but after spending all day playing gets good and puts bad words in the high score slots. When Monica comes home, chandler tries to give her a high-five, but his hand is stuck in the position from playing the game.
But throughout the rest of the scene, while Monica is trying to erase the bad words, we see chandler's hand as being fine several times, and not at all messed up. Later Phoebe comes over, and his hand it messed up again.