Here are a few of my favorite bits of scoundrel’s slang from Grose’s Classical Dictionary of the Vulgar Tongue, Revised and Corrected and The Slang Dictionary (grabbed those titles from this blog post):
Admiral of the Narrows Seas, person who from drunkenness vomits into the lap of the person sitting opposite them.
Anchor, to bring your ass to anchor, to sit down, to keep within the letter of the law.
Arch Rogue, Dimber Damber, Upright Man: Leader of a group of scoundrels.
Bachelor’s Son, a bastard
Bad Bargain, one of his majesty’s bad bargains; a worthless soldier
Ballast, money. A rich man is said to be well-ballasted. If not proud and over-bearing he is said to carry his ballast well.
Bang-up, first-rate, in the best possible style.
Bankruptcy List, a list that signifies, in pugilism, that one is completely finished.
Bellyful, a beating
Blunderbuss, a short gun with a wide bore, a stupid blundering fellow.
Catch Fart, servants so called from such servants commonly following close behind their master or mistress
City College, scoundrels’ nickname for Ironhook Prison
Cold cook, an undertaker. Cold cook’s shop, the crematorium
Cold meat, a corpse. Cold-meat box, a coffin
Cow Handed, Awkward
Crib, A house To crack a crib, to break open a house
Dab or dabster, an expert person. Most probably derived from the Latin adeptus
Distressed, in boxing when a man is distressed he is out
Do it away, to fence or dispose of a stolen article beyond the reach of probable detection
Floor, to knock down.—Pugilistic
Floorer, a blow sufficiently strong to knock a man down, or bring him to the floor. Often used in reference to sudden and unpleasant news
Ghost, “the ghost doesn’t walk,” a theatrical term which implies that there is no money about, and that there will be no “treasury”
Jack in an Office, an insolent fellow in authority
Land-shark, a sailor’s definition of a lawyer
Larrup, to beat or thrash
Larruping, a good beating or hiding
Lay down the knife and fork, to die. Compare pegging-out, hopping the twig, and similar flippancies
Lumber House, a house appropriated by scoundrels for the reception of their stolen property
My Uncle, a pawnbroker Cant
Nose, a thief who turns informer; a paid spy; generally called a policeman’s nose; “on the nose,” on the look-out
Nose, to give information to the police, to turn approver
Nose-ender, a straight blow delivered full on the nasal promontory
Number of his mess, when a man dies in the army or navy, he is said to “lose the number of his mess”
Rhino, ready money — Old
“Some as I know, Have parted with their ready rino.” – The Seaman’s Adieu, Old Ballad
Rhinoceral, rich, wealthy, abounding in rhino. At first sound it would seem as though it meant a man abounding in rhinoceroses
Scapegallows, one who deserves and has narrowly escaped the gallows a slip gibbet one for whom the gallows is said to groan
Scoundrel’s Grind, the relentless pressure in a scoundrel’s life
Snappers, pistols
Thumper, a magnificently constructed lie, a lie about which there is no stint of imaginative power
Thumping, large, fine, or strong
Togs, clothes; “Sunday togs,” best clothes
Vice Admiral of the Narrow Seas, a drunken man that pisses under the table into his companion’s shoes
Water of Life, gin
Githyanki Diaspora 
Excellent work, I’m going to be stealing quite a few of these. We’ve made a couple of turns of phrase fairly standard in our game:
To “show one’s hat” is to make your presence known, usually with bravado or self confidence. “You have the nerve to come around here showing your hat after what you and your boys pulled down the docks last night?” “I’ll head over there tonight and show my hat, maybe thump a few skulls, that’ll let ’em know who’s boss.”
“Crack” is a joke, usually in the context of sarcasm. “You want 25%? This is rousing good crack, yes? What makes you think your worthless hide is worth that much?” “I strung him up from the lamppost, just for crack.”
To “feed the eels” is to be killed and dropped in the canals. In contrast, to “feed the crows” is to be killed and left in the street for the Spirit Wardens to find.