WordNet (r) 3.0 (2006):

play false
    v 1: conceal one's true motives from especially by elaborately
         feigning good intentions so as to gain an end; "He
         bamboozled his professors into thinking that he knew the
         subject well" [syn: bamboozle, snow, hoodwink, pull
         the wool over someone's eyes, lead by the nose, play
         false]