Green’s Dictionary of Slang

(S.Afr.) a member of a politically orientated black youth gang.

1987		Frontline Feb. 24: Azasm – known as the Zim-Zims — remain in the Azapo fold [DSAE].
1990		R. Malan My Traitor’s Heart 258: In Soweto, youngsters who said Biko were dubbed Zim-zims, in honour of all the -isms in their ideological arsenal.