Green’s Dictionary of Slang

(W.I.) a general derog. description of a person.

[1827		Hamel, Obeah Man I 72: Her master need not brag so much of his new friends, who, bad as they looked, (‘fit only for the John-crows,’) still looked better than they were in reality].
1902		J. Speirs Proverbs of British Guiana 17: Ebery John crow t’ink he own picknie white.
1942		L. Bennett ‘Sweetie-Pie’ in Jam. Dialect Poems 9: Donkey tink him cub a race-horse, / John crow tink him pickney white.
1953		R. Mais Hills were Joyful Together (1966) 273: ‘John Crows,’ said Manny to Wilfie. ‘Jus’ like a lot of ole John Crows.’.
1980		(con. 1950s) M. Thelwell Harder They Come 36: Chu, you head favor jancro pickney.
1997		‘Q’ Deadmeat 149: One dem Jancrows fine hout, deh start bringeen dem frien an fuck up di place.
1999		(con. 1979–80) A. Wheatle Brixton Rock (2004) 69: I just stood there like a frightened john crow, staring at him.
2004		K-Lash-Nek-Off [song title] Jankrowville.