What's the weirdest blunder someone ever made in a game?

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QuaQuaMuzGo

I was playing a chess game with the new Sensei Karate Bot (3000) (with hints), and it made a big blunder by letting me play a brilliancy that won me a rook. Surprisingly, that would be the move I would've played in that position if I were black. It won't let me upload the file, though. Upload yours, please!