Green’s Dictionary of Slang

s’elp me tater! excl.

a general oath.

1837		‘Now!’ in Rum Ti Tum! in Spedding & Watt (eds) Bawdy Songbooks (2011) III 169: You may think it haf, but so help me tater, it is tr[u]e.
1845		J. Lindridge Sixteen-String Jack 79: Oh, Lor’, if you’d heard my blessed apologies—like nothing but the Arabain Nights, so help m’ tater!—jist a thousand and one rolled into one.
1860		Hotten Dict. of Modern Sl. etc. (2nd edn) 100: ‘S’help my bob,’ a street oath [...] Other words are used in street language for a similarly evasive purpose, i.e. cat, greens, tatur, &c, all equally profane and disgusting.
1860		Era (London) 20 May 4/3: ‘You’ll go and blab if I tells yer,’ said boy No. 2. ‘If I do s’elp me tater,’ replies No. 1.
1866		Wild Boys of London I 95/2: ‘Halleluja!’ said Jack, ‘you got him, so help me tater!’.
1874		Leeds Times 28 Mar. 6/5: He is bloomin’ well brewered, there’s no kid. He was on, s’help me tatur!
1875		Shields Dly Gaz. 11 Dec. 4/2: Yes, wagebone [i.e. vagabond], selp me Taters. I’ll choke yer when I cop yer agin.
1890		‘Doss Chiderdoss’ ‘Vagaries of the Vernacular’ Sporting Times 15 Mar. 1/3: A youngster’s oft corrected by his pater, / Should he happen to let slip from his adolescent lip / Such remarks as ‘S’elp me bob!’ and ‘S’elp me’tater!’.
1901		Bulletin (Sydney) 7 Dec. 19/1: He [...] just buzzed along like a sausage-machine, and because he put on no side, nor said ‘s’elp me tater,’ or any dashed thing, the boys wouldn’t believe him.
1919		E. Dyson ‘Repaired’ ‘Hello, Soldier!’ 96: S’elp me tater, it’s a gift / How they glues you all together.