Green’s Dictionary of Slang

minty n.

also mintee, mintie
[? link to Fr. minet, an effeminate young man]
(US gay)

1. an effeminate male homosexual.

[US]B. Rodgers Queens’ Vernacular 73: stereotype effeminate homosexual [...] mintie (’40s cf *hint of mint = a flavor of homosexuality). [Ibid.] 132: Vanity, vanity, thy name is Mintie.
[US]L. Kramer Faggots 233: Three little minties had rushed right into this very Ladies Room and felt her dress and its fabric’s texture.

2. a masculine lesbian.

[US]G. Legman ‘Lang. of Homosexuality’ Appendix VII in Henry Sex Variants.