Green’s Dictionary of Slang

banger n.1

[fig. use of bang v.1 (1)]

1. a notable lie.

Hanger Sporting ‘Flyleaf’ n.p.: A sportsman entire – who says nay, tells a banger [F&H].
[UK]W.S. Gilbert Engaged in London Assurance and other Victorian Comedies (2001) Act III: You are quite right, the word is bouncers. Bouncers or bangers; either will do.
[UK]R. Whiteing No. 5 John Street 77: They earn half-pence by well-told ‘bangers.’ They are sent out to lie to the grocer.

2. something large.

[Scot] Burns ‘The Reels o’ Bogie’ Merry Muses of Caledonia (1965) 154: His pintle was of largest size, / Indeed it was banger.
[UK]Taunton Courier 26 Apr. 10/2: A large apple was a ‘banger’.

3. something excellent, an outstanding example.

[UK]T. Morton A School For Grown Children II i: Ear-rings for me! Gemini, how genteel! what bangers!
[US] in R.G. Carter Four Brothers in Blue (1978) 3 July 452: The hat is a banger.
[Ire]A. Killilea Boyo-wulf at https://boyowulf.home.blog 5 May 🌐 And so he ruled, fightin’ the law, one against all, until that banger of a gaff stood empty.

4. (US black) in music, an outstanding success.

gigwise.com Sept. 🌐 Her self-confessed ‘glorified mix-tape’ features some absolute bangers this year: from Azealia Bank’s ’212’ to Hot Chip’s ‘Night and Day’.
Jeezy annotation to ‘Let Em Know’ on genius.com 🌐 Even though it might not be a club banger. Or it might not be a radio banger or none of that shit. It’s going to set a tone.
[UK]T. Thorne (ed.) ‘Drill Slang Glossary’ at Forensic Linguistic Databank 🌐 Banger – hit, successful song.