Green’s Dictionary of Slang

1. paper money [orig. UK but by mid-20C Aus. only].

1865		Leaves from Diary of Celebrated Burglar 21/1: Joe said there was ‘pap’ (notes) among it.
1879		‘Autobiog. of a Thief’ in Macmillan’s Mag. (London) XL 505: When we got into the rattler they showed me the pap; yes, there it was, fifty quid.
1898		Belfast News-Letter 11 Apr. 6/5: ‘Pap’ or ‘shinplaster’ for a banknote needs no explanation.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 7: It was pay night and it would be the pap for his terrible turk.
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Pap. Money.

2. (US) a newspaper.

1908

B. Fisher A. Mutt in Blackbeard Compilation (1977) 80: I have just received a San Francisco pap.