Green’s Dictionary of Slang

(N.Z. prison) an inmate who turns to prison officers for help when facing a tbreatening situation (rather than dealing with it themself).

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 130/2: one-one-one (also 111) n. an inmate who calls for help from prison officers when in a threatening situation, behaving like a victim.