Green’s Dictionary of Slang

(S.Afr.) a servile, subservient black person.

1975

S. Sepamla in New Classic No. l 12: I asked, what about my pass-book? Joe shook his head as if he really pitied me [...] There’s so much of the yes-baas in you that you can hardly see the difference between the paper you carry and the penis which is part of your body [DSAE].