MERRYMAN. The jack pudding, jester, or zany of a mountebank, usually dressed in a party-coloured coat.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
merkin * merry a-se christianNathan Bailey's 1721 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes