Green’s Dictionary of Slang

nanty! excl.

also nantee! nanti!
[nanty adv.]

stop! beware!

[UK]Sl. Dict. 234: nantee also means ‘shut up’ or ‘leave off!’.
[UK]Sporting Times 10 Apr. 3/3: Once or twice I ses, ‘Nanty, gents, nanty’.
[UK]R. Morton ‘O Lizer, Para-Lizer’ [lyrics] Lizer murmured ‘nanty’ – I want to kiss your brother Fred.
[UK]Sporting Times 6 Jan. 1/4: ’Ere, nanty, now, nanty! [...] don’t start no ’anky-panky with me or I shall dot yer!
[UK]A. Binstead More Gal’s Gossip 83: Nanty! Don’t put it about, but it’s a pinch — Honeymoon!
[UK]‘Doss Chiderdoss’ ‘Woman’s Wear’ Sporting Times 30 July 1/3: If fashion says ‘Nanty’ you’ll alter your mien.
[UK]P. Allingham Cheapjack 123: I doubled him up to quids. ‘Nanty!’ he said.