Green’s Dictionary of Slang

dollars or pounds sterling.

1939		Coshocton Trib. (OH) 8 Nov. 2/3: ‘I’m saying goodbye to a thousand smackeroos’.
1941		C. Brackett & B. Wilder Ball of Fire [film script] Smackaroos? — Smackaroos? What are smackaroos? [...] A smackaroo is a dollar, pal.
1944		C. Himes ‘Let Me at the Enemy’ in Coll. Stories (1990) 42: Fifty-five smackeroos an’ the day just half gone.
1951		M. Spillane Long Wait (1954) 34: A check revealed that the bank was short two hundred thousand smackeroos.
1961		William Randle ‘Payola’ in AS XXXVI:2 109: Slang is a large repository of words ending in -ola [...] : smackola.
1967		in S. Harris Hellhole 182: This party will pay you one hundred smackeroos, kid.
1972		R. Barrett Lovomaniacs (1973) 11: So she’s the star of six million smackeroonies worth of picture?
1978		L. Kramer Faggots 61: One million smackolas. Wouldn’t they help? [Ibid.] 363: I want my one million smackarolas!
1981		J. Sullivan ‘Cash and Curry’ Only Fools and Horses [TV script] Mr Ram [...] would hand over to us 4,000 lovely smackeroonyos.
1988		J. Milne Daddy’s Girl (1999) 27: I had a cheque for five-seven-two smackeroos.
1988		McGill Dict. of Kiwi Sl. 104/2: smackers/smackeroos dollars, previously pounds sterling, from the South American English ‘smacker’, a peso, which became US for dollar, perhaps helped by sound a silver dollar made hitting the counter.
1992		Times Herald (Port Huron, MI) 15 Jan. 9/1: Cost: One-hundred and fifty smackerolas.
1998		Dly Jrnl (Franklin, IN) 10 June 4/2: According to the rules of the game, some lucky fan would have chance to [...] win 2 million smackeroos.
2000		B. Wiprud Sleep with the Fishes 138: The reward was actually a hundred thousand smackeroos [i.e. dollars].
2001		K. Waterhouse Soho 87: ‘A hundred what?’ ‘Smackeroos. In readies. In your back sky-rocket.’.
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].