WordNet (r) 3.0 (2006):

flip out
    v 1: react in an excited, delighted, or surprised way; "he
         flipped when he heard that he was accepted into Princeton
         University" [syn: flip, flip out]
    2: go mad, go crazy; "He flipped when he heard that he was being
       laid off" [syn: flip, flip out]

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "flip out":
   anger, boil over, bridle, bridle up, bristle, bristle up, fidget,
   flutter, freak out on, get high on, get mad, get sore, glow,
   go pitapat, have the fidgets, have the shakes, heave, jerk,
   palpitate, pant, quake, quaver, quiver, reach boiling point,
   see red, shake, shiver, squirm, swell, swell with emotion, thrill,
   thrill to, throb, tingle, tingle with excitement, toss,
   toss and turn, tremble, tumble, turn on to, twist and turn, twitch,
   twitter, wiggle, wriggle, writhe