Originally, a labourer or husbandman: figuratively a rude, surly, boorish fellow. To put a churl upon a gentleman; to drink malt liquor immediately after having drunk wine.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Churk * Cinder GarblerNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes