A cook’s shop, under Furnival’s Inn, where many attornies clerks, and other inferior limbs of the law, take out the wrinkles from their bellies. DIP is also a punning name for a tallow-chandler.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Dip * DippersNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes