Green’s Dictionary of Slang

rab n.¹

(W.I./UK black) a lawless, rowdy person.

1976

cited in Allsopp Dict. Carib. Eng. Usage (1996).

In phrases

make rab (v.)

(W.I.) to make a fuss, to complain.

1956

S. Selvon Lonely Londoners 8: The English people starting to make rab about how too much West Indians coming to the country.