The Collaborative International Dictionary of English v.0.48:

boner \boner\ n.
   1. an embarrassing mistake.

   Syn: blunder, blooper, bungle, foul-up, flub, botch, boo-boo,
        misdoing.
        [WordNet 1.5]

   2. one who bones food.
      [PJC]

WordNet (r) 3.0 (2006):

boner
    n 1: an embarrassing mistake [syn: blunder, blooper,
         bloomer, bungle, pratfall, foul-up, fuckup,
         flub, botch, boner, boo-boo]