He then bespattered the youth with abundance of that language which passes between country gentlemen who embrace opposite sides of the question; with frequent applications to him to salute that part which is generally introduced into all controversies that arise among the lower orders of the English gentry at horse-races, cock-matches, and other public places. Allusions to this part are likewise often made for the sake of the jest. And here, I believe, the wit is generally misunderstood. In reality, it lies in desiring another to kiss your a[rse] for having just before threatened to kick his; for I have observed very accurately, that no one ever desires you to kick that which belongs to himself, nor offers to kiss this part in another.
It may likewise seem surprizing that in the many thousand kind invitations of this sort, which every one who hath conversed with country gentlemen must have heard, no one, I believe, hath ever seen a single instance where the desire hath been complied with;—a great instance of their want of politeness; for in town nothing can be more common than for the finest gentlemen to perform this ceremony every day to their superiors, without having that favour once requested of them.
The History of Tom Jones, a Foundling. Book VI, Chapter ix.