Green’s Dictionary of Slang

1. (UK Und.) to buy and sell stolen property.

1821

D. Haggart Autobiog. 98: I flashed the wedge to Mrs Dougall for three quids.

2. (US Und.) to acquire through pickpocketing.

1900

A.H. Lewis ‘Mulberry Mary’ in Sandburrs 9: He used to get in his hooks deep an’ clever now an’ then, an’ most times Billy could, if it’s a case of crowd, flash quite a bit of dough.

3. (Aus. Und.) to pass counterfeit money.

1904

Sun. Times (Perth) 17 Jan. 12/4: The judge said my actions in ‘flashin’’ the coins showed I was not an experienced criminal.