Green’s Dictionary of Slang

cracker n.2

[SE crack, to make a sharp noise; they all ‘go off’]

1. a pistol.

[UK]Smollett Peregrine Pickle (1964) 138: Here’s my sapling, and I don’t value your crackers of a rope’s end.

2. the penis.

[US]Maledicta IV:2 (Winter) 193: The grocery, the butcher’s and the sweet shop are all represented as well as the greengrocer’s. Thus there is […] cracker (goes off like a firework).

3. (N.Z.) a cartridge.

[NZ]McGill Dict. of Kiwi Sl. 31/2: cracker cartridge; c.1900.
[NZ]McGill Reed Dict. of N.Z. Sl. [as cit. 1988].

4. see crack n.1 (2a)