Green’s Dictionary of Slang

1. those in authority or power, the Establishment.

1922		Appleton Post-Crescent (WI) 13 May 7/1: Flapper Dictionary they – Used by Flappers with tone of disgust to denote the older generation.
1984		B. Ellem Doing Time 198: they: the authorities.
1985		T.R. Houser Central Sl. 52: they say [...] In response to ‘why were you in jail?’ the reply, ‘They say I did a robbery.’.
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 They. The authorities.

2. (US black) a wife or mistress.

1946

Mezzrow & Wolfe Really the Blues 220: They or them people means, not two or more persons, but a man’s wife or mistress.