Meaning of whammo

wham•mo

Pronunciation: (hwam'ō, wam'ō), [key]
— Informal. Informal.
—interj.
  1. (used to indicate the sound of a blow, collision, falling object, etc.).
—n.
  1. immense energy; vigor: a movie with plenty of whammo to please the kids.
—adj.
  1. characterized by such a strong effect: a show with a whammo ending.
—adv.
  1. wham.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.