Green’s Dictionary of Slang

knob v.¹

1. (also do the knob) to hit in the face or head.

1818		Sporting Mag. II. 211: He knobbed his adversary well .
1953		T.A.G. Hungerford Riverslake 26: Look out, Jerry – he’ll do the knob any minute!

2. usu. of a man, to have sexual intercourse.

1952		D. Sanderson Dark Passions Subdue 189: ‘I saw her come downstairs with that bum Stephen. They’d been knobbing, I think’ [Simes:DLSS].
1988		T. Thorne Dict. Contemp. Sl. 298/2: ‘If you were in with the Royal family and you were a girl, you’d definitely want to knob Prince Andrew or someone’.
1993		I. Welsh Trainspotting 312: Ye still knobbin Kelly?
1999		K. Sampson Powder 369: The fucking manager was knobbing the big cheese from the record company.
2000		K. Smith Run Naked, Run Free 131: Why did I want him to knob me? No one ever had. A wank with school friends was the limit of my sexual experiences [Simes:DLSS].
2005		P. Howard Curious Incident of the Dog in the Nightdress 119: If you must know I knobbed Pikey’s bird!
2015		I. Welsh Decent Ride 326: Easy for that cunt tae say, when eh’s knobbin ma fuckin burd!

3. to masturbate.

1981		R.A. Spears Sl. & Euph. 222/2: knob [...] to masturbate.
1987		Graffito (Sydney) [D]addies suck their daughters cunnies and knob their clits and open their pussie lips [Simes:DLSS].

In compounds

knob artist (n.)

a successful seducer, a womaniser.

1984		McConville & Shearlaw McConville & Shearlaw Slanguage of Sex 115/2: ‘[K]nob artist’—a man admired for his ‘pulling power’.
1992		Poetry Rev. 82 62/1: Both [...] occasionally trot out this ‘poet-as-international-knob-artist’.

In phrases

knob on to (v.)

to be in love with; to woo.

1887

H. Baumann Londonismen (1902) 107/1: to knob on to sich hängen an, sich verlieben in; he knobbed on to her er machte ihr den Hof.

In exclamations

knob it! [sense 2, as synon. for fuck it! excl.]

a general phr. of dismisssal.

1999

Guardian Sport 1 Jan. 16: Oh, knob it. I’ll start tomorrow.