Green’s Dictionary of Slang

1. (US black) one who indulges in any variety of oral sex; thus generic for a male homosexual (see cite 1972 [2]).

1916		H.N. Carey Sl. Venery I 38: cannibal—A person who tongues one of the opposite sex.
1960		Jrnl Social Therapy vi 170: Head-hunters, cannibals and kid-fruits are fellators [Simes:DLSS].
1972		B. Rodgers Queens’ Vernacular.
1972		P. Fisher Gay Mystique 137: [T]hese ‘Hollywood and Greenwich Village cannibals’ are constantly on the lookout for new stuff, persons who are not homosexuals [Simes:DLSS].
1987		personal ad in restroom Murray & Murrell Lang. Sadomasochism (1989) 48: Cannibal, 29, male, well-built, would like to meet new ‘victims’ soon, also for light B & D, perhaps some S & M.
1992		J.W. Dagion (ed.) Meat Rack 37: I swear he had a tongue four inches long [...] usThat cannibal almost ate me alive [Simes:DLSS].

2. (US tramp) an older homosexual tramp who travels with a young boy.

1927

‘Jargon of the Und.’ in DN V 437: A type of homosexual pervert. Also ‘cannibal’.