Green’s Dictionary of Slang

(a) one who hits (hard).

1842		Whip & Satirist of NY & Brooklyn (NY) 23 Apr. n.p.: The lives of the [...] suckers, pimps, thieves, pickpockets, bullies, skivers and bangers.
1959		A.J. Liebling A Neutral Corner: Boxing Essays (1990) 107: ‘[Ingmar] Johannson’s a big, strong guy,’ Whitey [Bimstein] said, ‘and he’s a banger. He could knock [Floyd] Patterson’s brains out.’.
1977		P. Hamill Flesh and Blood (1978) 44: ‘He’s a banger.’ [...] ‘Banger? He’s a goddam killer.’.
2000		F.X. Toole Rope Burns 80: She was a banger who waded in winging shots from all angles.

(b) (US black/prison) any form of knife.

2000		Ebonics Primer at www.dolemite.com 🌐 banger Definition: a boxcutter, razor, or knife. Example: Son, that nigga from the way was hit in the neck with a banger!
2000		Other Side of the Wall: Prisoner’s Dict. July 🌐 Banger: A knife. Also called a burner or a shank.
2011		G. Hayward Corruption Officer [ebk] cap. 16: These are no makeshift bangers or shanks.
2012		‘Dutch’ ? (Pronounced Que) [ebook] ‘Gimme the goddamn bangas,’ YaYa gritted. Blue [...] handed YaYa a short ice-pick like weapon made of sharpened steel.

(a) a hypodermic syringe.

1950		Goldin et al. DAUL 22/2: Banger. A hypodermic needle; an addict of hypodermic drug injections. ‘I ain’t hustlin’ (stealing) with dudes (fellows) that use a banger. They’re poison.’.
1953		Anslinger & Tompkins Traffic In Narcotics 303: banger. A hypodermic needle.
1992		Bentley & Corbett Prison Sl. 82: Rig is another name for fit or outfit. (Archaic: banger).

(b) one who injects narcotics.

1950		see sense 3a.
1953		Anslinger & Tompkins Traffic In Narcotics n.p.: banger. [...] an addict who takes drugs by injection.
1997		A. Highcrest At Home on the Stroll 188: An addicted coke banger can go through a handful of needles in no time.

(a) one who copulates.

1966		T. Keyes All Night Stand 86: That’s all I need; the Bangor Banger.
1966		P. Willmott Adolescent Boys of East London (1969) 56: I could see right away she was a right banger.
2012		(con. 1980s) I. Welsh Skagboys 24: The missus, Janey, is an old banger for sure, defo a looker in her day, and still worth one at a push.

(b) the penis [note banger n.³ (1); like a sausage it ‘spits’ when it gets put in the oven n. (1)].

1980

Maledicta IV:2 (Winter) 193: The grocery, the butcher’s and the sweet shop are all represented as well as the greengrocer’s. Thus there is […] banger (a sausage, so-called because it spits when put in the oven = chuff-box).