This is a true story and anybody who has the latest Chess Scotland Magazine will confirm it.
The Cesenatio (Itlay) Open 2008.
White (let's call him C.M, and is graded 2091). Black (lets us call him V.O. an IM graded 2468)
This position arose:
Black has just played 19...Kd7c7.
The move before that White played 19.Kd2 and went to the toilet.
Whilst away Black played 19...Kd7c7 and started Whte's clock but
never wrote his move down.
White comes back and sees that Black has not written down his 19th
move so thinking he had forgot to stop his clock, he stops his clock.
Black plays 20...Qxg2!! ??
Black has just played two moves on the trot.
White actually went to win and after the game his opponent confessed he
"had tried to pull a fast one."
I've seen pawns go from the 5th to the 7th rank in one move.
Bishop change their square colour from d2 - b5 giving a check.
I've seen a guy so messed up in time trouble he started capturing his own pieces.
I even heard of a player playing in crowded conditions castling with a Rook from another board!
(he had lost his h1 Rook so he castled with an a1 Rook on the board next to him.)
But not writing your move whilst your opponent is off board and nicking a move is a new one.
Here is the game.It's a real cracker.
Now remember Black has had two moves on the trot so to make this playable
I have added a White move 20.Rb1was not played.
Serves him right!
Something similar happened to me once in a very casual game. I had a pawn advanced and it was stopping my opponent doing anything and had him blocked in. I returned to the board and the cheeky blighter had removed it! What he'd neglected to see though was that it was also in my way. Won very quickly after that.