WordNet (r) 3.0 (2006):

show off
    v 1: display proudly; act ostentatiously or pretentiously; "he
         showed off his new sports car" [syn: flaunt, flash,
         show off, ostentate, swank]

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "show off":
   boast, brag, brandish, display, disport, exhibit, exhibitionist,
   expose, flash, flaunt, flaunter, grandstand, grandstand player,
   grandstander, hot dog, parade, please the crowd, showboat, swagger,
   trot out