Green’s Dictionary of Slang

(US prison) one who carries contraband, e.g. drugs, tobacco, for a more influential prisoner.

2023

Rayman & Blau Riker’s 169: If business was good, I have three holsters. And these guys [...] I would spot-check them. I’d grab them and say, “Hey, where is it? Where is it?” And if they didn’t tell me that it was up their ass, I would cut them off.