Green’s Dictionary of Slang

(US black) other people’s, usu. in ref. to an unspoken commodity, e.g. cigarettes, alcohol or clothes.

1929		H.W. Brecht Downfall 146: He smokes O.P.’s.
1939		A. Bessie Men in Battle 58: Each man carried a cigarette case in which he collected butts; his own or o.p.’s.
1956		E. Hunter Second Ending 382: What do you smoke? I smoke O.P.’s.
1957		‘Nino Culotta’ They’re a Weird Mob (1958) 86: ‘You are all smoking those things I smoke.’ ‘Never knock back O.P.’s.’.
1984		W.J. Caunitz One Police Plaza 81: I only smoke O.P.’s . . . other people’s . .
1986		C. Bowles G’DAY 99: If they’re always borrowing cigarettes they smoke O.P.’s (Other People’s).
1991		New Yorker 2 Sept. 27: We asked Chris what brand of cigarette she smoked. ‘O.P.’s . . . Other People’s. When I buy my own, I get one of the cheapies.’ .
2003		McGill Reed Dict. of N.Z. Sl. 149: OP’s Other people’s cigarettes, usually requested by someone giving up cigarettes and not having any on them but desperate at the sight of another person smoking. ANZ.