Green’s Dictionary of Slang

1. fighting, esp. in a group.

1969		(ref. to 1950s) R.L. Keiser Vice Lords 50: Humbugging is further subdivided: fighting between rival clubs is gangbanging.
1971		H.E. Roberts Third Ear n.p.: gang banging v. fighting, especially in a group.
1972		T.M. Kochman ‘The Kinetic Element in Black Idiom’ in Kochman Rappin’ and Stylin’ Out 161: Other terms, such as [...] ‘gang-banging,’ and ‘rumble’ are ‘noise’ terms.
1988		J.D. Vigil in Ethos 439: Unpredictable forms of destructive behavior, such as [...] excelling in gang-banging.
2005		W.D. Myers Autobiog. of My Dead Brother 164: I wasn’t down for no gangbanging, but it was as if we were being sucked into it.
2023		Rayman & Blau Riker’s 247: Some of [the teenager prisoners] are gangbanging.

2. being and living the life of a member of a US youth/prison gang, usu. in Los Angeles; also attrib.

1985		‘Jennifer Blowdryer’ Modern English 61: gang banging (n): Gang activity.
1988		NWA ‘Gangsta Gangsta’ 🎵 Homies all standing around, just hangin / Some dope dealin, some gang bangin.
1991		L. Bing Do or Die (1992) x: He told me [...] that he had started in gangbanging at ten.
2000		W. Shaw Westsiders 32: Another myth about gang-banging was that members were supposed to support each other when they were in trouble.
2001		Source Aug. 36: If you are a rapper, stay away from the gangbangin’ style, ’cause dudes will press up on you, and it’s not worth it.
2023		Rayman & Blau Riker’s 69: There wasn’t any gang banging, but in other houses [i.e. parts of the prison] Latin Kings and Ñetas were oppressing people.