Green’s Dictionary of Slang

(US) a stupid person.

1960, 1975		Wentworth & Flexner DAS.
1963		J. Rechy City of Night 52: Theres gonna be hobos! homos! and momos! in Our Park long after youve grown deaf and dumb.
1978		R. Price Ladies’ Man (1985) 86: La Donna would be sitting there with some big momo from Duluth front row centre.
1997		(con. 1970s) G. Pelecanos King Suckerman (1998) 20: Standing there, sipping their drinks like a couple of mo-mos.
2000		Ebonics Primer at www.dolemite.com 🌐 momo Definition: a person of low intelligence Example: Listen to me, you dumb fuckin’ momo!