Time to hang up your chess pieces after that fail.
Opponent blunders on move #5 in my recent OTB

My OTB rating WAS 1887. After this tourney I expect I will lose about 17 points. I played in the Under 2000 section and finished with 1 win, 2 draws and 2 losses. (After finishing the first game of the day in 25 minutes, I didn't want to wait 5.5 hours until the second game started, so I withdraw from round 6 and headed home early.)
This was this weekend in San Diego. It was the Recession Buster Open.
Although it's rare, here's proof that 1800+ players can be capable of absolute bone-head blunders. This game is from a recent OTB tourney of mine:
My opponent resigned here, as I'm about to win the e pawn too.
After he castled, I immediately knew, of course, that he blundered away the knight. His disappointment and amazement were very visible when I took it. He couldn't believe he blundered away the piece.
After the game, he explained to me he mixed up his move order. He intended to play d5 (or normally always does play an early d5) and THEN castle.
He was about ten or fifteen minutes late to the game, and possibly was trying to move a bit quicker than normal, to make up for his lost time.
I was actually disappointed to win this way. Since I was already out of the running for any prize money, I would rather have had a good game. But it does make for my shortest OTB win ever, both in terms of moves and time.