Oops, I meant j'adoube

The attached position comes from a final round game played at Street Chess today. Black is clearly winning, and the full point would secure a share of second place. But last rounds, and a shortage of time, can do strange things to the thought process, and Black fell victim to this. He started with the obvious 1. ... Rb1+ intending to meet the forced 2.Bg1 with 2. ... Rxg1+. That was until his hands got out in front of his brain, and he picked up the bishop on f6. Sure Bd4 forces mate, but only if White decides to pass, which is not allowed under the Laws of Chess. In fact Black did not even complete whatever move he had to play, Instead he let out a strangled cry and waved the bishop around for a while before simply shaking hands with an absolutely delighted White.
After the game I suggested that maybe he could have tried to bluff his opponent by using the bishop to stir his coffee (or clean his ears) before putting it back on f6. The other option was of course to try the old "j'adoube" trick, claiming you meant to say it *before* you touched the piece. But having already given the game away by his reaction, I doubt this would have worked.
So a pair of naughty hands cost Black a tie for second, and instead left both players sharing third place with a couple of other beneficiaries.