Green’s Dictionary of Slang

gangster n.

[? its rebel image, but note ganja n. (1)]

1. (US black) marijuana.

[US]C. Cooper Jr Weed (1998) 121: Gangster (because everybody used to think gangsters smoked it).
[US]A. Young Snakes (1971) 53: We been smokin on this gangster for an hour look like.
[US]‘Iceberg Slim’ Airtight Willie and Me 44: I lit up two bomber sticks of dynamite gangster.
[Aus](con. 1945–6) P. Doyle Devil’s Jump (2008) 51: ‘What is it?’ ‘Gage [...] Texas Tea. Mexican Spinach. Maitland madness. Loco weed. Indian Hemp. Gangster. Marijuanna.’.

2. (US black) a cigarette.

[US]D. Claerbaut Black Jargon in White America 65: gangsters n. cigarettes.

3. (US black) a troublemaker; an aggressive, abusive person.

[US]E. Folb Runnin’ Down Some Lines 238: gangster [...] 2. Troublemaker. 3. Physically aggressive or abusive person.
[Aus]B. Ellem Doing Time 190: gangster: a young lout who pretends to be a big-time crim. In this case the word gangster is often prefixed by the phrase ‘would-be’.
[Aus]Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Gangster. A prisoner who establishes an influence as a tough, particularly by consorting with others of that ilk. Often used pejoratively to describe a young lout who pretends to be a big time criminal.
[US]Bentley & Corbett Prison Sl. 42: When one of the meaner, stronger inmates uses force and intimidation to achieve things, he is referred to as a gangster.

4. (US black) a rebellious, non-conformist individual.

[US]E. Folb Runnin’ Down Some Lines 120: The gangster [...] can be a physically violent or abusive person, intractable and immune to any verbal strategies designed to dissuade him. But, unlike the out-and-out hardhead, he has style, courage, and a ganglandlike code of ethics. He is the tough guy of TV and movies.
[Aus]R. Park Fence Around the Cuckoo 128: ‘Can I take Flash Jack?’ ‘Not to a sheep station. Not that little gangster of a dog. The Big Noise would have a fit.’.

5. (US prison) HIV/AIDS.

[US]Other Side of the Wall: Prisoner’s Dict. July 🌐 Gangster: HIV. ‘Be careful around him. He got that gangster.’ See also ‘Monster.’.