WordNet (r) 3.0 (2006):

fuckup
    n 1: someone who makes mistakes because of incompetence [syn:
         bungler, blunderer, fumbler, bumbler, stumbler,
         sad sack, botcher, butcher, fuckup]
    2: an embarrassing mistake [syn: blunder, blooper,
       bloomer, bungle, pratfall, foul-up, fuckup, flub,
       botch, boner, boo-boo]