A club instituted by the Independents and Presbyterians, to commemorate the decapitation of King Charles I. Their chief fare was calves heads; and they drank their wine and ale out of calves skulls.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Calves * CalibogusNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes