Feisty and variants. Just occurred to me that "feisty" is a good descriptor of the FiST IMO
FEISTY, FIESTY, FYSTEE, FEISTEE
Randoms:
PWRFIST, POWRFST
TRBOFST (see also "redundant")
PARTYBX (inspired by member Lilpartybox)
FSTPRTY (Fast Party (or Fist Party ouch))