I am having too much fun reading A Classical Dictionary of the Vulgar Tongue, published in 1788 to provide definitions of the sort of vile, unmannerly slang employed by 18th-century streetfolk.
It was created by William Grose, and as The Public Domain Review notes, Grose's goal was to craft a dictionary of all the naughty words that Samuel Johnson deemed too grody for his famous dictionary a few decades earlier. As they continue …
While a good deal of the slang has survived into the present day — to screw is to copulate; to kick the bucket is to die — much would likely have been lost had Grose not recorded it. Some of the more obscure metaphors include a butcher's dog, meaning someone who "lies by the beef without touching it; a simile often applicable to married men"; to box the Jesuit, meaning "to masturbate; a crime, it is said, much practised by the reverend fathers of that society"; and to polish meaning to be in jail, in the sense of "polishing the king's iron with one's eyebrows, by looking through the iron grated windows". Given this was the era of William Hogarth's famous painting Gin Lane (1751), it's not surprising to find the dictionary soaked through with colourful epithets for the juniper-based liquor: blue ruin, cobblers punch, frog's wine, heart's ease, moonshine, strip me naked. The Grose dictionary also contains hundreds of great insults, like bottle-headed, meaning void of wit, something you can't say about its author.
The whole dictionary has been beautifully scanned here by the Internet Archive.