Green’s Dictionary of Slang

(US) a young male prostitute.

1986		R. Campbell In La-La Land We Trust (1999) 10: The rain had washed all the baby prostitutes and twangy boys, the chicken hawks and queer bashers, the gonifs and petty grifters off the four corners of Hollywood and Vine. [Ibid.] 96: It was the big mamas and papas who gave birth to the petty pimps, hookers, ass smashers, juice squeezers, child buyers, twangy boys, and street gonifs.
1995		R. Campbell Wizard of La-La Land (1999) 133: A twangy boy’s a male who sells his ass for the carnal delectation and entertainment of men of the homosexual persuasion but claims not to be a homosexual himself.