Green’s Dictionary of Slang

1. copulating.

1841		‘After Many Spreeish Years’ Gentleman’s Spicey Songster 18: After many shagging years, / How sweet it is to come / To the move of beauty, when / She moves her little bum.
1932		in V. Randolph Pissing in the Snow (1988) 147: She was glad of it, and you never seen such a shagging match.
1985		B. Humphries Traveller’s Tool 13: Us diplomats […] run them pretty close in the shagging stakes.
2004		J. McCourt ‘Vilja de Tanquay Exults’ in Queer Street 298: Yes, me, illegitimate – out of some yank’s / Shaggin’ bollocks what rogered me wayward mum.

2. (orig. Irish) a semi-euph. for fucking adj.

1946		R. Grinstead They Dug a Hole 75: Those shagging Taffies in the next field were laying out theirs with a tape.
1958		(con. 1940s) B. Behan Borstal Boy 352: Shagging lies about all the [...] money they got away with.
1965		L. Dunne Goodbye to the Hill (1966) 51: He could have gone places if he hadn’t been such a shagging layabout.
1971		(con. WWII) B. Aldiss Soldier Erect 9: God, what a sodding, shagging, scab-devouring misery it all was!
1989		H. Leonard Out After Dark 19: The last shaggin’ bus is gone. I’ll have to hoof it.
1991		R. Doyle Van (1998) 381: Wha’ were yeh doin’ in a shaggin’ disco bar? Bimbo asked Bertie.
2000		N. Griffiths Grits 115: Great fuckin work ur no, ut’s a load uv fuckin shite in places, like a diffrunt shaggin language.

3. as an infix.

1973		H. Leonard Da (1981) Act I: He knows too shaggin’ much.
1989		H. Leonard Out After Dark 28: Do yous not know Killiney-shaggin’-Hill when it’s there in black and white in front of yous?
1995		Sydney Morn. Herald 21 Oct. 163/3: ‘I love Dublin,’ says O’Connor [...] You don’t have to be James shagging Joyce any more’.