Green’s Dictionary of Slang

1. an ice pick or a weapon that resembles one.

1939		R. Chandler ‘Trouble Is My Business’ in Spanish Blood (1946) 199: A guy who needs that much gun ought to use a pick.
1992		Bentley & Corbett Prison Sl. 87: Pick An ice pick type weapon. A pick can be a sharpened screwdriver, bedspring or any round, sharpened object.

2. (Aus. prison) a hypodermic syringe; the needle employed.

1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Pick. A hypodermic syringe.
1991		R.G. Barratt ‘A Tour de Bondi’ in What Do You Reckon (1997) [ebook] [T]hey used to drag the junkies out of the brascoes with picks hanging out of their arms.
1999		D. Looser ‘Boob Jargon’ in NZEJ 13 34: pick n.The actual hypodermic needle attached to a syringe.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 140/1: pick n. a hypodermic needle.