The Collaborative International Dictionary of English v.0.48:

boo-boo \boo-boo\ n.
   1. an embarrassing mistake.

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

   2. a minor injury, such as an abrasion on the skin; --
      child's talk.
      [PJC]

WordNet (r) 3.0 (2006):

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