BUNG-NIPPERS,
Cut purses, who with a short sharp Knife, and a horn Thumb, used to cut Purses. Since the wearing of Purses is out of Fashion, they are called Files or Pick-Pockets.
The Vulgar Tongue originally collected by Grose, 1811.
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).