A gentleman. A well dressed man. Mung kiddey. Mung the gorger; beg child beg, of the gentleman.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Goosecap * Gospel ShopNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes