backslang it, v. — Green’s Dictionary of Slang

backslang it v.

[? link to back slum under back adj.²; the term predates the linguistic variety of backslang, while there seems to be no link to slang n.¹ itself; ? link to sling one’s hook v. (1)]

1. to make a deliberate detour to avoid meeting a certain person or persons.

1812

Vaux Vocab. of the Flash Lang. in McLachlan (1964) 225: back-slang: [...] to go a circuitous or private way through the streets, in order to avoid any particular place in the direct road, is termed back-slanging it.

2. to leave by the back door, thus to leave surreptitiously, quietly.

1812		Vaux Vocab. of the Flash Lang. in McLachlan (1964) 225: back-slang: to enter or come out of a house by the back-door [...] is termed back-slanging it.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1859, 1860		Hotten Dict. of Modern Sl. etc.
1864, 1867, 1870		Hotten Sl. Dict.
1871–82		B.M. Carew Life and Adventures.
1882		Sydney Sl. Dict. (2 edn) 1: Back Slang It - To go out the back way; to get away quickly.
1895		Crowe Aus. Sl. Dict. 5: Back Slang It, go out the back.
1909		J. Ware Passing Eng. of the Victorian Era 14/1: Back slang it (Thieves’). To go out the back way.

3. (Aus.) to request lodgings from strangers as one travels through the back country.

1898

E.E. Morris Austral Eng. 14/1: In the back-blocks [...] where hotels are naturally scarce and inferior, the traveller asks for hospitality [and] is always made welcome. There is no idea of anything underhand on the part of the traveller, yet the custom is called back-slanging.