The mouth. Gift of the gab; a facility of speech, nimble tongued eloquence. To blow the gab; to confess, or peach.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
to fuzz * gab stringNathan Bailey's 1721 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes