Green’s Dictionary of Slang

an act of sexual intercourse.

1994		J. Wambaugh Finnegan’s Week 268: That bitch ain’t gave me some knobbin since she told me she wants a firm commitment.
1998		I. Welsh Filth 16: She’s been too long without a good fuckin knobbin.
2015		I. Welsh Decent Ride 107: Ah’m thinkin aboot the epic knobbin ah gied that Suicide Sara-Ann Lamont.