Connotations

I was taken aback by what seemed to me an excessively sexual allusion in one of Lovelace's letters: "If thou likest her, I'll get her for thee with a wet finger, as the saying is!" (L239, 810). But when I looked it up, I found that the primary allusion is to spinning, and the spinner's habit of wetting the forefinger with the mouth. The sexual connotation is surely there, but secondary.