To polish the king’s iron with one’s eyebrows; to be in gaol, and look through the iron grated windows. To polish a bone; to eat a meal. Come and polish a bone with me; come and eat a dinner or supper with me.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Pole * PollNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes