Green’s Dictionary of Slang

1. the act of pawning; thus in pop, in pawn.

1815		‘The Gin Shop’ in Vocal Mag. 2 Jan. 4: My clothes went to my Uncle’s in pop.
1838		Kendal Mercury 17 Nov. 1: How the deuce am I get to get inexpressibles out of pop if I pay you half a couter?
1867		‘Johnny Cross’ ‘Collar Butcher’ in Orig. Pontoon Songster 24: He put his clothes ‘in Pop,’ to buy a shot-gun.
1889		‘’Arry on the Ice’ in Punch 23 Feb. 85: ’Ardly got your old skates out of pop.
1900		‘Doss Chiderdoss’ ‘In-and-out Running’ Sporting Times 17 Feb. 1/4: Much watch-chain on show— / It was mostly in pop, and was, if you must know, / Just out.
1901		Sydney Sportsman (Surry Hills, NSW) 3 July 1/6: Half her jewels / Was in pop.
1914		Bulletin (Sydney) 10 Sept. 40/4: Me furnichur’s mostly in pop, / Me weddin’ ring’s gone up the spout; / But Billo must ’ave ’s wee drop / No matter wot we do without.
1935		G. Ingram Cockney Cavalcade 230: I thought you’d give me more than I could get in pop.

2. the pawnbroker’s; note pop shop under pop v.²

c.1820		‘Railroad to Hell’ in C. Hindley Curiosities of Street Lit. (1871) 33: No wonder that Pop-ticket women and wags, / Are dressed up in nothing but patches and rags. / Their dresses and shawls for strong liquor they’ll swop, / Yes, Tagrag and Bobtail must go to the pop.
1922		Joyce Ulysses 307: Pawning his gold watch in Cummins of Francis street where no-one would know him in the private office when I was there with Pisser releasing his boots out of the pop.