Green’s Dictionary of Slang

1. (orig. US) to fool around, to tamper, to fiddle, usu. in a destructive clumsy manner, occas. used as a synon. for the expression ‘to busy one’s self’ with anything, but it cannot be legitimately used of honest, useful work, except when such work is either badly done or is undertaken as a recreation rather than as a legitimate business.

1883		N.Y. Times 26 Aug. 6/5: ‘To monkey’ is a neuter verb [...] Its primary meaning is to busy one’s self in ways other than utilitarian. The amateur painter, or musician, ‘monkeys’ with art, and the political theorist who invents impracticable reforms may be said ‘to monkey’ with politics.
1884		C.F. Lummis letter 1 Dec. in Byrkit Letters from the Southwest (1989) 122: Probably you think that I am monkeying around somewhere near the Azrizona line tonight.
1890		Bulletin (Sydney) 16 Aug. 20/3: ‘The court simply affirmed the decision of the lower court,’ was the reply. ‘And that is,’ said Kemmler, ‘that I’ve got to be touched off by this electric machine. Well, the sooner it’s over with now the better. I’m tired of this monkeying for I guess the law’s all right.’.
1892		E.J. Milliken ’Arry Ballads 6: Your monkeyings mar every pageant.
1896		W.C. Gore Student Sl. in Cohen (1997) 11: monkey v. To fool; to fritter away one’s time.
1903		A. Binstead Pitcher in Paradise 123: The humiliating prospect of [...] explaining to an unfriendly alien that I had been monkeying with his money.
1905		Marvel III:60 31: That’s my ’and-cart you’re monkeying around with!
1906		S. Ford Shorty McCabe 8: Now as a general thing I don’t monkey with the ponies. [Ibid.] 50: I wouldn’t have monkeyed around after dark on that perpendicular landscape for twice the money.
1915		Wodehouse Psmith Journalist (1993) 186: I can’t go monkeying about with the paper that way.
1916		A. Stringer Door of Dread 85: Yuh and your gorilla-gink ’ve done consider’ble monkeyin’ wit’ me [...] and there’s been doin’s in this dump that’ll call for consider’ble ventilatin’.
1917		F. Packard Adventures of Jimmie Dale (1918) I ii: I’ll show you how it’s stuck on, if you monkey around here!
1921		P. & T. Casey Gay-cat 44: A yegger! [...] A strong-armer! Now I know, I don’t monkey with Mr. Whitey-scar.
1922		M.E. Smith Adventures of a Boomer Op. 11: It looked to me that to monkey around getting him riled up, would be too much like flirting with Kingdom Come.
1923		Wodehouse Leave it to Psmith (1993) 516: I’ve got no time to waste monkeying about with safes.
1932		(con. WWI) L. Mann Flesh in Armour 263: ‘War’s too big a thing [...] to monkey about finding out that this lord general’s a dud’.
1933		J. Spenser Limey 35: He’s been monkeyin’ around with another guy’s girl.
1935		A. Christie Three Act Tragedy (1964) 143: Doctors are interfering devils [...] They monkey about with fellows’ lives.
1938		D. Runyon ‘Dancing Dan’s Christmas’ in Runyon on Broadway (1954) 257: He is not a guy to monkey with.
1947		F. Brown Fabulous Clipjoint (1949) 109: We’ve monkeyed around with him too long.
1947		N. Marsh Final Curtain (1958) 182: Supposing Miss Orrincourt did monkey with the thermos.
1959		E. De Roo Go, Man, Go! 81: At the garage [... the Corvette was all they had in there. Three of them monkeyed with it.
1960		P. Rabe Murder Me for Nickels (2004) 27: Nobody fixes the gadgets except us, nobody monkeys with the wires.
1966		P. Willmott Adolescent Boys of East London (1969) 139: You go in and you mess about and you start getting told off and before long you’re monkeying about and playing up.
1987		B. Chatwin Songlines 159: Make sure the kids don’t monkey around with the Land Cruiser.
2000		F. Kellerman Stalker (2001) 174: The car had been monkeyed with prior to the kidnapping.
2000		Observer Rev. 19 Mar. 6: We don’t like the way he is proposing to monkey about with the Brunswick Centre.
2006		News Jrnl (Mansfield, OH) 17 Dec. 25/1: When a husband would rather monkey around with his monkey than monkey around with his wife, you know the marriage is in serious trouble.
2014		E. Pruitt ‘Houston’ in ThugLit Mar. [ebook] ‘Never monkey with the supply’.
2020		D. Winslow ‘The San Diego Zoo’ in Broken 129: He loses track of the times he’s told not to “monkey around” on his shift.

2. (US) to cheat, to defraud.

1889

Nat. Police Gaz. (NY) 23 Nov. 6/2: The next story on the list is [...] how a Mrs. Craig monkeyed old man Craig out of $1,000.