Green’s Dictionary of Slang

smash n.2

1. [late 18C–1900s] (UK Und.) counterfeit money [? it smashes the hopes of those who use it].

2. [mid-19C+] (also smesh) cash, usu. change [rhy. sl.; the note has also been ‘broken’].

3. [late 19C] (UK prison) tobacco, in its role as prison ‘cash’.

In compounds

smash-feeder (n.) [SE feeder] (UK Und.)

1. [mid-19C] a silver spoon.

2. [mid-19C–1900s] a Britannia-metal spoon, made from a metal resembling silver but in fact an alloy of tin and regulus of antimony; the best counterfeit coins were made from such spoons.

In phrases

do a smash (v.)

[mid-19C] (UK Und.) to pass counterfeit money.