Green’s Dictionary of Slang

(US) loud, large and impressive.

1968		N. von Hoffman We are the People Our Parents Warned Us Against 72: Tom [...] has parts of the older wham-bang, shut-up-kid, working-class culture in his background.
a.2003		‘Rev. of Busy Bodies’ on ClassicVideo.ch 🌐 Stan and Ollie work in a sawmill. It’s unusually hard, whambang, slapstick stuff for the Boys to tackle, but it is an excellent example of the way the team builds on a single gag, from initial good intentions to ultimate mayhem.