Green’s Dictionary of Slang

b.o.s. n.

[abbr.]

(US P.R. gang) a beating on sight.

[US]1st C. Bone 🌐 On the subject of Initiation & Violation. When G & D was started they did true indeed have codes such as B.O.S. (Beating On Sight) which was a form of violation, but Hoover saw that that only hurt our brothers & made them turn on the nation.