JUCKUM-Gage,
a Chamberpot. Tip me the Jockum-Gage, Give or hand me the Looking-Glass. Rum Jockum-Gage, a Silver Chamber-Pot.
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Entry taken from 1736 Canting Dictionary, by Nathan Bailey.
The Vulgar Tongue originally collected by Grose, 1811.
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).