1) An embarrassing mistake 2) Big boo-boo 3) Big goof 4) Big mistake 5) Blockheaded blunder 6) Blockheaded move 7) Bloomer 8) Blooper 9) Blunder 10) Boo-boo 11) Botch 12) Botch-up 13) Bungle 14) Cause for a head-slap 15) Cause of a red face 16) Chef, at times 17) Damfool thing 18) Dimwit move 19) Dumb mistake 1) Blooper 2) Blunder 3) Botch 4) Bungle 5) Clanger 6) Error 7) Flub 8) Fumble 9) Gaffe 10) Misstep 11) Mistake 12) Slip 13) Solecism 
Boner is slang for a blunder, mistake.
Refers to a mental mistake, which changes the course of a game significantly.
a person or thing that bones.