Green’s Dictionary of Slang

a euph. for fuck v. in its various senses.

1932		G.S. Moncrieff Café Bar 31: ‘O, muck it all!’ cried Joe. [Ibid.] 74: Muck you, get out of my way!
1938		J. Curtis They Drive by Night 278: Go on. Muck off.
1943		M. Harrison Reported Safe Arrival 11: Wiv that titfa on yer loaf, an’ all ... Muck me if I ever see anything like it!
1945		J. Maclaren-Ross Swag, the Spy and the Soldier in Lehmann Penguin New Writing No. 26 49: I mucked off home for a month, see?
1951		D. Stivens Jimmy Brockett 129: The radiator was pushed up over the engine and the water was running down the street. I’d mucked her, good and proper.
1959		G. Slatter Gun in My Hand 207: I bring him here and he just mucks off.
1960		(con. WWII) G. Sire Deathmakers 109: Think of how they would have mucked your mother and cut your heart out.
1962		A. La Guma Walk in the Night (1968) 68: Now let’s muck off.
1962		H. Livings Nil Carborundum (1963) Act I: Oh muck off, Taffy.
1967		(con. 1940s) M. Dibner Admiral (1968) 264: You mucked it all.
2010		J, Lanier You Are Not a Gadget 51: [S]oftware that could only be created by [...] evolution, which cannot be reverse-engineered or mucked with in any accessible way.