Green’s Dictionary of Slang

1. London [Franklyn suggests that it was a destination towards which one travels on the frog under frog (and toad) n.].

1857

‘Ducange Anglicus’ Vulgar Tongue We will go to frog and toe. Thieves coming up to London with plunder.

2. (US Und.) New York City.

1859		Matsell Vocabulum 35: frog and toe The city of New-York. ‘Coves, let us frog and toe,’ coves, let us go to New-York.
1866		Nat. Police Gaz. (NY) 3 Nov. 3: Dutch returned immediately to ‘frog and toe’ with a gay set of whiskers, which he had raised in ‘stur.’.
1881		Trumble Sl. Dict. (1890).