Green’s Dictionary of Slang

cracker n.1

[SE crack/crack n.3 (4)]

1. (UK Und.) the backside.

[Ire]Head Canting Academy (2nd edn).
[UK]B.E. Dict. Canting Crew n.p.: Cracker, c. an Arse.
[UK]New Canting Dict.
[UK]Bailey Universal Etym. Eng. Dict.
[UK]Grose Classical Dict. of the Vulgar Tongue.
[UK]Lex. Balatronicum.

2. (S.Afr.) in pl., sheep-skin trousers.

C.G.H. Literary Gazetter 2 Sept. 238: Old Crackers alias leather breeches.
Autobiog. of Sir Harry Smith II 348: You [...] would laugh to see our motley group, with every costume of a mean kind [...] the 72nd’s men with crackers.
[UK]H.A. Bryden Kloof and Karroo 199: Klaus looked pretty well ‘baked’ even in his old leather ‘crackers’.
[SA]C. Pettman Africanderisms 131: Crackers Trousers of prepared sheep-skin, largely used in the early days by the settlers, and so named because of the cracking noise which they made at every move of the wearer.