WordNet (r) 3.0 (2006):

dirty trick
    n 1: an unkind or aggressive trick

Moby Thesaurus II by Grady Ward, 1.0:

48 Moby Thesaurus words for "dirty trick":
   artful dodge, artifice, bag of tricks, blind, bluff, bosey, catch,
   chicanery, chouse, curve, curve-ball, design, device, dirty deal,
   dirty pool, dirty work, dodge, double-dealing, duplicity,
   falseheartedness, fast deal, feint, fetch, ficelle, foul play,
   gambit, gimmick, googly, hocus-pocus, joker, juggle, pass,
   perfidiousness, perfidy, ploy, ruse, scheme, scurvy trick, shift,
   sleight, sleight of hand, sleight-of-hand trick, stratagem,
   subterfuge, treacherousness, treachery, trick, wile