I play in the Chicago Industrial Chess League (CICL) for my employer DRW. I generally play one of the lower boards, but I do pretty well. Two nights ago, I played possibly the best chess game of my life... and lost.
How? By touching the wrong piece. I had a choice of two recaptures - one that would win the game, and one that would lose. If I had simply moved quickly, that would've been bad enough, but I actually noted the problem with the first recapture, and then did some sanity checks for the other move. Content that all was good, I started my move by picking up the bishop to be captured, AND THEN PICKED UP THE WRONG CAPTURING PIECE. I realized it immediately, but by then it was too late. I resigned a few moves later.
The worst bit is I found a strong move on 18. (see below, I'm playing white) - and I saw that position 3 moves earlier. I don't always play this well when I'm rested - let alone after a 12 hour work day... which of course just makes the blunder that much more painful.
Moral of the story? When you're winning, when you're tired (or both!). STOP! Check it again. Check each bit, write it down and check it a third time. Then if your sure, make the move.
This one burned. Hopefully it stung enough that I won't do it again.
Anyway, for your viewing pleasure, here is my wonder-blunder:
Side to move: