Green’s Dictionary of Slang

a euph. for bugger n.¹

[1838		R.S. Surtees Jorrocks Jaunts (1874) 241: I brought down a pair of kickseys and pipe-cases, intending to have a round with the old muggers, but the snow put a stop to all that].
1950		‘Neville Shute’ Town Like Alice 294: Joe Harman’s a clumsy mugger with a car.
1957		‘Neville Shute’ On the Beach 237: ‘I’ve got nothing to give away on you muggers,’ he said, grinning.