Uncle Ben, n.² — Green’s Dictionary of Slang

Uncle Ben n.²

[play on Uncle Tom n. + whiteness of Uncle Ben’s brand of rice]

(US gay) a homosexual black man who prefers white men; thus a term of abuse.

1972		B. Rodgers Queens’ Vernacular 63: black man who prefers white sex partners. [...] Uncle Ben.
1991		C. Hiaasen Native Tongue 278: ‘May I see your driver’s license, please?’ ‘Get serious, Uncle Ben.’.