The Collaborative International Dictionary of English v.0.48:

flag-waver \flag-waver\ n.
   an extreme bellicose nationalist.

   Syn: chauvinist, jingoist, jingo, hundred-percenter.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

flag-waver
    n 1: an extreme bellicose nationalist [syn: chauvinist,
         jingoist, jingo, flag-waver, hundred-percenter,
         patrioteer]