Green’s Dictionary of Slang

(US) a general term of abuse, a foolish person.

1930		S.J. Perelman in Marschall That Old Gang o’ Mine (1984) 94: Ordinary mooks like you and me have been stuffing their blotters and backs of envelopes in safe deposits.
1973		M. Scorsese Mean Streets [film script] 87: You can’t call me a mook!
1976		R. Price Blood Brothers 83: We’re all sittin’ there an’ some mook puts ‘High Noon’ on the juke.
1988		S. Selvon Eldorado West One 76: I ain’t standing up here like a mook, man. I going circulate and meet the boys.
1995		J. Stahl Permanent Midnight 72: A succession of Armani’d mooks.
1996		(con. 1964-65) B. Thorpe Sex and Thugs and Rock ’n’ Roll 135: Don’t trust that bastard Joey [...] he’s a fuckin’ mook!’.
2001		J. Stahl Plainclothes Naked (2002) 112: One of the mooks yelled at her, and the rest joined in.
2005		Mad mag. Sept. 46: It’s my class. The other mook was a sub.
2008		T. Piccirilli Fever Kill 101: Mooks who’d discovered too late that running touchdowns might get them laid [...] but it wasn’t going to get them anwhere far in the world.
2011		G. Phillips ‘Slicers’ Serenade of Steel’ in Pulp Ink [ebook] ‘Sal, stake me a twenty, won’t you?’ Surely he could raise the freight among these mooks.
2014		Wiley ‘On a Level’ 🎵 I don’t know what they told you, but I’m not a mook.
2020		D. Winslow ‘Sunset’ in Broken 210: Mooks like Maddux are restless by nature.