Green’s Dictionary of Slang

foolish, stupid.

1890		‘’Arry’s Visit to the Moon’ in Punch Christmas Number in P. Marks (2006) 168: A whole howling mix-up of ‘mug’ booky, dog-owner and rough.
1898		J.D. Brayshaw Slum Silhouettes 34: Oh well, if he’s mug enough to take up wiv her, let him look after her.
1901		Sydney Sportsman (Surry Hills, NSW) 27 Mar. 1/2: So the mug pony patron parted up 7s 6d for Mountain’s entrance ticket.
1905		‘Doss Chiderdoss’ ‘An Improved Understanding’ Sporting Times 14 Jan. 1/4: ’Twas a match in the making, folks hadn’t a doubt; / And her people seemed willing to bring it about, / Though the suitor was of the ‘mug’ brand.
1910		Bulletin (Sydney) 15 Dec. 35/1: Why, if yer silly mug enuff to go diggin’ big ’oles ’arf over Melbourne with a pick an’ shovel, you deserve orl yer likely to git [...].
1915		Drew & Evans Grafter (1922) 84: ‘[H]e muzzled me. I suppose he thought I was silvery, He’s a mug garrotter, or he wouldn’t have picked me out’.
1918		‘Sapper’ Human Touch 83: If some one was mug enough to try and spot the lady coming up from Epsom in the train, when Pete was manipulating the cards – well, surely enough has been said about the three-card trick.
1923		F. Anthony ‘Helping Out Gus’ in Me And Gus (1977) 11: I’m always mug enough to accept the offer.
1948		S.L. Elliott Rusty Bugles I iii: You’re a mug liar.
1959		G. Slatter Gun in My Hand 213: Mug ape. What’s eating ya? Clueless bastard!
1972		A. Chipper Aussie Swearers Guide 62: Note the national fondness for the word mug, as in mug copper, mug gunner and ‘You’ve gotta protect the mugs’.
1979		J. Morrow Confessions of Proinsias O’Toole 5: Poor deluded mug me!
1983		J. Byrell (con. 1959) Up the Cross 103: He’d never been seen to [...] make any mug moves.
1996		J. Byrell Lairs, Urgers & Coat-Tuggers 119: The official excuse he offered for that sudden mug move was that the fly-poop 49 kg [...] was ‘too much of an impost for this horse’.
2007		N. ‘Razor’ Smith Raiders 84: He was in for what I class as futile, pointlessly viiolent mug-crimes.