When you're playing chess and you take so long thinking about what move you're going to make that you end up making an idiotic move you spotted in the first 5 seconds but forgot about later on.
During a game of chess, after thinking about his move for 20 minutes ...
Ryan: Ah ha! Eat that! You have been had my friend.
(Jon swoops in and takes Ryan's queen)
Jon: Looks like the ol' Chess Alzheimer's got you again. Checkmate, fool.
Ryan: (Tears up)
Jon: It's okay man. Let's go watch Upstream Color. It'll cheer you up.
Ryan: No thanks, I like stories that are actually good. You know, with a beginning, middle, and end. Fuck that $hit. I'm going to play Halo. (flips chess board and leaves with dignity)