Hey, it's honest dishonesty...
(From Men in Hats. Click on the thumbnail for full sized hilarity.)
Not only is this hysterical, it's so true. So. Damn. True. Not only have I had this happen to me, I've done it. And so have you. Sometimes, when you've been cornered in a debate, and are clearly wrong, you want something... anything to prove you're superior to your opponent.
It's a variation on a great Simpson's line:
Ned Flanders: Gosh, Homer, looks like you're missin' a piece of your puzzle!
Homer Simpson: Oh yeah? Well it looks like you're missing a wife! Because she died!
Ned: [chastened] heh. Yeah. I walked right into that one, Homer. Good one.