WHISTLE,
the Throat. Wet your Whistle: liquor your Throat.
the Throat. Wet your Whistle: liquor your Throat.
Entry taken from 1736 Canting Dictionary, by Nathan Bailey.
Whistle in the 1811 Vulgar Tongue
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).