Mine uncle’s; a necessary house. He is gone to visit his uncle; saying of one who leaves his wife soon after marriage. It likewise means a pawnbroker’s: goods pawned are frequently said to be at mine uncle’s, or laid up in lavender.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
To Vowel * UnderstrapperNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes