Signs you're a bad chess player

You never heard of the 50 move rule and so you and your opponent trade down to bare kings and the game goes on forever. 

You sacrifice a bishop and your opponent gets the compensation.

You have a chance to capture via en passant but insists you can do it on your next move.

You attempt to en passant his rook when he moves it past your rook.

thank you everyone for sharing your mistakes

I still do that, and have to correct it when I go through my post-mortem 

In time trouble, everything is possible... 

When a pawn makes it to the 8th, you insist that it stays a pawn.

 I was playing a OTB game and was in time trouble so I was moving very quickly along with my opponent. I was pushing my pawns and quickly slapping the clock, but then I pushed my hand forward to move and then hit the clock, unfortunately I didn't move the pawn. Fortunately, my opponent was a friend of mine and let it pass. 

Bahahaha so true :)

Your opponent's idea for a king sacrifice works well

Many years ago, at an OTB tourney, a group of us were talking (hey, it was between rounds!); one fellow mentioned than a woman (non-player) asked him why our eyes were so bloodshot, since we "don't do anything!"

8.Rxg7+ and 11.Ng5 come to mind. Unsound sacrifices?

You play the Barnes opening (1.f3, 2.Kf2) and believe it's a forced win for white.

You don't know why, but whenever you march your king into the battlefield you get free pieces, but you prefer not to get anything at all.

Your rating slipped from a one two spaces long (assuming each character is 1 space long) to one four spaces long even through it droped only around 150 points.

You believe you should be a GM because your rating is well over 3000 (rounded quite severely).

You manage to lose in just one move (without resigning or forfeiting).

You believe that one-dimensional chess is better than "normal" chess.

As soon as your opponent presses the "clock start" button the clock gives you an instant loss so the tournament director has kindly already announced your results before the start of the tournament.

 Lol, posporov, I get the feeling you've found that book. (And thought the exact same thing.) I wonder if a book like that would have a blank cover.

1. You are forbidden to play in any tournament

2. Your rating dropped from 1200 to -1745 in one game

3. You practice one opening so much that you don't know how to play chess outside of that opening

4. Your best rating was unrated

5. You don't know how to annotate

A long time ago I was playing in the last round of a tournament where I had been practically crushed by the highest rated players in all previous games. For the last game, I ended up playing against an unrated player who had taken up chess a couple months before the tournament. I was so bombed out about my performance that I started making moves without even paying attention to the board when all of a sudden....I gave my queen away. I was in immediate shock and right then and there, I decided I was going to play the rest of the game for a win. Well, it was a tough game....but as it usually happens with beginners (my opponent), he kept hanging pieces here and there and eventually I got an advantage and won the game. Once I said 'Checkmate' my opponent just sat there looking perplexed and out of the blue he just yelled in frustration: "Man, I must really suck at this game if even with a queen advantage I can't win!!" Now this happened while other games were taking place and to our surprise, the other players just started laughing.

Been there, got the t-shirt!

It takes your opponent a while to realize that you're not playing suicide chess.