2632. You heard somebody say the queen is worth the most points so you protect her instead of you king!

2633. You think that the king is lousy, so you remove him from the board!

2634. you buy expensive chess engines to help you find mate in 1

2635. You think there's a mate-in-one move from the very start for white. 

2636, You think black moves first,

2637. At the start, you tell the opponent to roll a dice to choose who goes first.

2328. While playing versus a tadpole, Both Rybka AND Fritz tell you you ought to quit chess and join the high school curling team after analyzing your game.

File clearing is getting rid of every piece except king.

2639. You refuse to play in coffeeshops and parks on a tangible set because you're afraid your opponent will discover that you use Rybka, Fritz, Chessbase, Houdini, etc. etc. to cheat.

2640. Your cat beats you at chess.

Just one of those days.

2641: you don't know that rooks could move

Note: 2642 is in the diagram.

2643. You always try to move your bishop in the first move

2644. You think you are forced to open up that way you castle on your fourth move.

2645. You argure about whether e4 or d4 is the bewst first move.

2646. You argue about whether knights or bishops are better.

2647. You're still in denial that the "en passant" exists.

2648:

Blue Knight 9 (no. 2640), my cat DID beat me at chess!!!!  Many years ago I played correspondence chess - yep, snail mail! I'd have up to 20 games at once.  So I had little magnetic boards set up in a cupboard, each board with the current position from one game set up.  I made a move in a particular game and sent the scoresheet off.  A few days later I received the reply - mate!!!!!  My board was set up with the wrong position.  I couldn't work out why.  Some weeks later I found my cat in the cupboard carefully pushing the pieces around with its paw.  A few weeks later I got my revenge by beating the cat at tennis.

you abandon the game when you are losing.

you waste your time till your opponent won due to time expire. with this, your pride seem not affected so much.

2651: You play boncloud chess because you think that your king should lead his troops to battle.