The mouth. I gave him a wherrit, or a souse, across the chops; I gave him a blow over the mouth. See Wherrit.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Chopping * Chop-stickNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes