whizzer

1. (UK, slang) A pickpocket.Examples: "In order better to appreciate the use of argot among thieves, a visit to a few public bars of the third-class public houses of Kennington or in the immediate vicinity of the Elephant and Castle would prove of great value, as hoisters, whizzers, tea-leaves, con-heads, broadsmen and brass nobs […]"; "It is doubtful if the Victorian Londoner needed any warning, for the artful mobsmen, toolers, whizzers and dippers, together with their stickman accomplices, were everywhere in the crowds, in the underground, on railway trains […]"; "They were whizzers (pickpockets) but they would also take part in burglaries."UKslang

2. (historical) Synonym of whizgig (“spinning toy”).Synonyms: whizgighistorical