Say bad luck and see a four leaf clover fall on your opponent's head.
Worst Thing To Do On Your First Move
Accidentally kick the table with enough force that it tips. And it being a circular table, it starts to roll. It rolls on the uneven floor until it hits the far wall. The wall is made of plaster and the table goes right through it! Behind the now-broken-wall there was a meeting of Very Important People - and they simply DO NOT appreciate the disruption. But! It doesn't stop there. The table keeps rolling - right out the window! Falling from a height of 20 floors - it lands on a truck. The dented truck pulls away from the stop-sign. But then stops unexpectedly when a speeding car rushes by. The momentum helps the table start off on it's journey once more. Only, you can't see where it is headed, because unlike the table you are still on the 20th floor of the partly destroyed room, with a group of angry VIP's and an amused opponent.

Accidentally kick the table with enough force that it tips. And it being a circular table, it starts to roll. It rolls on the uneven floor until it hits the far wall. The wall is made of plaster and the table goes right through it! Behind the now-broken-wall there was a meeting of Very Important People - and they simply DO NOT appreciate the disruption. But! It doesn't stop there. The table keeps rolling - right out the window! Falling from a height of 20 floors - it lands on a truck. The dented truck pulls away from the stop-sign. But then stops unexpectedly when a speeding car rushes by. The momentum helps the table start off on it's journey once more. Only, you can't see where it is headed, because unlike the table you are still on the 20th floor of the partly destroyed room, with a group of angry VIP's and an amused opponent.
Good one!
Forget that your not playing Shogi and try to drop a piece on the board and the peoples at the tournament that your in think you tried to cheat so they make you automatically lose.
Beginner mistake: use your queen to take your opponents queen.
"Checkmate!"
"You can't do that!?"
"Well, you said the queen can move anywhere!"

1.e4 e5 2.Qh5 and then you accidentally touch your king.
I know a guy that told me when he was a kid, him a several friends played chess. They went to a tournament and one opened his game with the bizzare1. e4 e5 2. Qh5??. When he played the last move he asked the kid he was playing if he had a sticker under his king promting him to look. He claimed that he had to move is king then and play the disasterious 2...Ke7??. That dude is a NM now so I guess either the tricked worked in almost every game or he learned how to play damn well. LOL

A: *by accident touches pawn*
B: Touch and move!
A: But-
B: No buts! Touch and move!
A: Fine... *moves pawn only 1 mm* Don't blame me, okay, I moved it.
B: ...

Playing 1.Nf3 and at the same time sneeze while farting so that the board and pieces are full of bugger and saliva make the opponent vomit because of the stench that came out of your arse and mouth due to the expired minced meat with rotten ognoins you ate that morning.

Playing 1.Nf3 and at the same time sneeze while farting so that the board and pieces are full of bugger and saliva make the opponent vomit because of the stench that came out of your arse and mouth due to the expired minced meat with rotten ognoins you ate that morning.

Thinking that it was a bullet game when it was a two hour game and knock over all the pieces
Or the other way round
pass