Green’s Dictionary of Slang

nonsense! humbug! rubbish!

1827		R.B. Peake Comfortable Lodgings I iii: sir h.: [Aside] Gammon!
1837		‘Grey Dolphin’ in Bentley’s Misc. Apr. 352: The word was ‘Gammon!’.
1849		Thackeray Pendennis I 196: ‘Gammon,’ said Mr. Spavin. ‘This ain’t the way to town; this is the Fenbury road, I tell you.’.
1850		(con. 1843) Melville White-Jacket (1990) 122: ‘Blast you! you old rascal; I’ll have you licked for that! Tell me his name, some of you!’ turning round to the bystanders. ‘Gammon!’ cries a voice at a distance.
1854		Delhi Sketch Bk 1 July 82/1: ‘Gammon, Doctor,’ says I, ‘shure I’m the Commander-in-Chief’.
1860		Bell’s Life in Sydney 1 Sept. 3/1: Mary didn’t faint, bul threatened to jump out, to which Purtle replied ‘gammon’.
1861		T. Hughes Tom Brown at Oxford (1880) 111: ‘If you begin making a slave of yourself to that Miller, he’ll very soon have you down to a glass of water a day.’ [...] ‘Gammon.’.
1870		E. Greey Queen’s Sailors III 2: Gammon! You ain’t a-going to persuade me to that, sir.
1882		Vancouver Indep. (WA) 30 Nov. 2/1: Gammon! I’ll come up and draw the badger. Where is it gating?
1888–94		‘Walter’ My Secret Life (1966) II 303: ‘What have you been doing?’ ‘Nothing but examining.’ [...] ‘Oh! Gammon,’ said Nelly.
1890		B.L. Farjeon Mystery of M. Felix I 98: ‘Because you were frightened?’ ‘Gammon!’.
1895		Coburg Leader (Vic.) 16 Nov. 4/2: Braddy says the ‘They Says’ get home on Oily Gammon. Gammon! we know they don’t.
1901		‘Miles Franklin’ My Brilliant Career 81: Gammon! That’s what makes my kisses so nice.
1911		Gem 30 Sept. 22: Gammon!