Men of wit, in Ireland, who in the night amuse themselves with cutting inoffensive passengers across the face with a knife. They are somewhat like those facetious gentlemen some time ago known in England by the title of Sweaters and Mohocks.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Chafed * ChalkingNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes