Green’s Dictionary of Slang

buttock v.

[buttock n.]

to have sexual intercourse; thus buttocking n., sexual intercourse.

[UK]Hell Upon Earth 3: The Buttock and File, that is, such as go abroad in a good borrow’d Habit, with a pretended Maid, who catching some senseless Woodcock in their wheedling Snare, bring him home, where, after a good Treat for Buttocking, they retaliate his Favour, by diving into his Breeches for the remainder of his Cash.

In derivatives

buttocking (n.)

(Aus.) criticism.

[Aus]P. Temple Dead Point (2008) [ebook] Steady on [...] Man’s entitled ro give his team a bit of a buttocking.

In compounds

buttock mail (n.) [SE mail, payment, tax]

a fine imposed for fornication.

[UK]D. Lyndsay Satyre of Thrie Estaits (1604) 114: I gat gude payment of my Temporall lands, My buttock-maill, my coattis, and my offrands.
[UK]W. Scott Waverley II 122: D’ye think the lads wi’ the kilts will care for yere synods and yere presbyteries, and yere buttock-mail, and yere stool o’ repentance?

In phrases