Green’s Dictionary of Slang

rusty adj.2

[? Somerset dial. rusty, gross, obscene]

lecherous, amorous.

[UK]Marston Malcontent I vi: Nay, he is the rustiest-jawed, the foulest-mouthed knave in railing against our sex.
‘Letter from a Missionary Bawd’ in Carpenter Verse in English from Tudor & Stuart Eng. (2003) 427: Them once, for charity, I thought to take, / But seeming rusty Napps, I turn’d them back.
[UK]London Jilt pt 1 24: She [...] continually preached to me that those old Rusty blades who did it only once in four and twenty hours were the best and gave most Money.
[UK]Motteux (trans.) Gargantua and Pantagruel (1927) II Bk IV 272: A bawdy bachelor, talking with an old trout was saying, Remember, rusty gun. I will not fail, said she, scourer.
[Aus]Sun. Times (Perth) 17 May 1/1: The spectacle of the ‘rusty’ old inslinger with 100 nieces is diverting.
[Aus]Truth (Sydney) 29 Jan. 5/3: I’ve no doubt she loved him awful, / That there rusty feller, shure.
‘Esther Williams — Get a Li'l Like the Fishes Do’ in 🌐 Maybe when he blows that rusty load it’ll be different.
[US]Trimble 5000 Adult Sex Words and Phrases.
Digga D. ‘No Diet’ 🎵 Got a rusty ting from South with the mouth / [...] / I’ma buss in her mouth by all means.