Green’s Dictionary of Slang

gob! excl.

God!

1830		Ely’s Hawk & Buzzard (NY) 26 June 4/2: ‘By Gob! here comes the Colonel, we’ll pump him!’.
1833		W. Carleton Traits and Stories of Irish Peasantry I 270: By Gob, by Gog, by Gad, by Gor, and by Gorra.
1895		Truth (Sydney) 12 May 4/7: By gob, we’ll stop payin’ our taxes.
1900		Sporting Times 5 May 1/5: Be gob, he thought he had only to guide her round the turns.
1922		Joyce Ulysses 240: Gob, that’d be a good pucking match to see.
1934		H. Roth Call It Sleep (1977) 99: Be-gob, he’ll be havin’ me talk like a Jew. Sure!
1939		‘Flann O’Brien’ At Swim-Two-Birds 64: Gob you’re getting a paunch.
1947		C. Mann ‘The Ring on the Hill’ Light in the Valley 203: Be gob, you great loafin’ hound.
1962		P. Larkin letter 20 Feb. in Thwaite Sel. Letters (1992) 341: Gob – I’m being pursued by a mad poetess.