WHIZBANG
whizbang, whizzbang
(noun) a firecracker that (like the whizbang shell) makes a whizzing sound followed by a loud explosion
whizbang, whizzbang, whizbang shell
(noun) a small high-velocity shell; it makes a whizzing sound followed by a bang when it hits
Source: WordNet® 3.1
Etymology
Noun
whizbang (plural whizbangs)
(dated) A type of firework that made a whiz before exploding
(dated) A small artillery shell
(by extension) Someone or something that holds an explosive amount of success, skill or effectiveness.
She [Agatha Christie] has produced a whizzbang surprise which I am unable even to hint at without spoilsporting.
Source: Wiktionary