Green’s Dictionary of Slang

1. (US tramp) drugged or adulterated liquor, derived from nitroglycerine; a ‘knockout’ drug; thus peterman, peter-thrower, a thief who uses ‘knockout drops’; pete job, any form of criminality that involves the administration of knock-out drops.

1898		Omaha Dly Bee (NE) 15 Nov. 5/3: A ‘Pete’ job means a job where knockout drops are used. Criminals using drugs are known as ‘Petermen’.
1899		J. Flynt Tramping with Tramps 396: ‘Knock-out drops’ are also ‘peter’.
1900		Flynt & Walton Powers That Prey 92–3: The next morning John Bladen was unable to present himself at the offices of the A. A. & B., and he stated later that he must have been given ‘peter-drops’.
1907		Salt Lake Herald (UT) 25 Aug. 4/2: ‘You know what is a peter player?’ [...] ‘When comes in with money, too much money, he gets a little something in his drink. Like t’is.’ He showed the boy a small vial [...] ‘T’at is peter’.
1914		Jackson & Hellyer Vocab. Criminal Sl. 64: Amongst gamblers and badgers a ‘peter’ is a sleeping potion, a ‘knockout,’ such as hydrate of chloral.
1928		C. Panzram Journal of Murder in Gaddis & Long (2002) 116: Peter-man [...] Sometimes used to describe a man who slips a peter or knock out drops in another’s drink (a Keeley).
1933		D. Maurer ‘Junker Lingo’ in AS VIII:2 27: Among the addicts dope in general is known as gow, junk, or peter (any kind of knockout drops).
1959		J.E. Schmidt Narcotics Lingo and Lore.
1968		G. Slatter Pagan Game (1969) 153: Every small town has its characters: Stainless Steel who had seen the light [...] Joey who was only eighteen shillings.
1969		R.R. Lingeman Drugs from A to Z (1970) 205: peter chloral hydrate, a sedative.
2001		ONDCP Street Terms 17: Peter — Depressants.

2. (UK Und.) nitroglycerine.

1924		S. Scott Human Side of Crook and Convict Life 19: Pretty near blowed the windows out we did — used such a lot of gelignite and peter.
1933		Ersine Und. and Prison Sl.