So many criminally useful terms with olde-tymey flair!
Back Slang It: Thieves used this term to indicate that they wanted “to go out the back way.”
Batty-Fang: Low London phrase meaning “to thrash thoroughly,” possibly from the French battre a fin.
Don't Sell Me a Dog: Popular until 1870, this phrase meant “Don’t lie to me!” Apparently, people who sold dogs back in the day were prone to trying to pass off mutts as purebreds.
Got the Morbs: Use of this 1880 phrase indicated temporary melancholy.
Half-Rats: Partially intoxicated.
Jammiest Bits of Jam: “Absolutely perfect young females,” circa 1883.
Kruger-Spoof: Lying, from 1896.
Mafficking: An excellent word that means getting rowdy in the streets.
Mutton Shunter: This 1883 term for a policeman is so much better than a “pig.”
These come from a 1909 publication, linked at Mental Floss, which culled these, among 56 magnificent examples (check out Dickens' door-knocker and the cut of his gas-pipes, rowr). You'll go enthuzimuzzy to use them all!