Green’s Dictionary of Slang

1. the member of a pickpocket gang who is handed the stolen goods by the actual pickpocket and who must also try to hinder any attempts to capture their confederate by police or public.

1861		H. Mayhew London Labour and London Poor IV 282/2: One of the women on some pretext steps to the door and passes it [i.e. a stolen watch or wallet] to the ‘stickman’ standing outside.
1911		T.A. Dorgan ‘Daffydills’ in El Paso Herald (TX) 8 Sept. 8: The old stick man [was] now merely an outside man for Cahtah’s crap game.
1977		D. Powis Signs of Crime 202: Stickman The confederate of a pickpocket or skilled shoplifter to whom stolen property is handed and whose other task is ‘accidentally’ to impede pursuit of the actual thief if he is detected by the loser.

2. a store detective.

1980

(con. 1971) W. Sherman Times Square 52: The stickman was staring straight at him. I’ve blown it, he thought.