The study and documentation of colloquial language, from medieval beggar cant to Gen Z TikTok coinages.
The world's leading resource on English slang, compiled by Jonathon Green. First published in 2010 as a three-volume hardback, it now lives online (free). The oldest entries are "arse" and "bollocks", both attested roughly a thousand years ago in Anglo-Saxon glossaries. Green finds a new earliest-known citation at least every couple of weeks.
Francis Grose, a former militia captain so fat it was said he had to be tied to his bed to stop rolling off, published the "Classical Dictionary of the Vulgar Tongue" in 1785, compiled by prowling London's seedy neighbourhoods. He recorded gems such as strangle-goose for a poulterer. Eric Partridge collected soldiers' vocabulary from the first world war -- pip squeak and whizz bang were shells named for their sounds; toothpick was a bayonet; a Blighty one was a wound serious enough to send a soldier home. His "Dictionary of Slang and Unconventional English" appeared in 1937.
Social-media diffusion has shortened the half-life of new terms dramatically. Words race from avant-garde to mainstream to death (when parents start using them) in months. Slang like skibidi -- a near-meaningless term from videos about talking toilets -- is "designed to be transient". Tony Thorne of King's College London collects gang and drill-music slang (such as matic for gun, nank for "to stab").
Green gives Australians top marks for creativity (coinages popularised by comedian Barry Humphries include technicolour yawn for vomit and siphon the python for urinating). The English style is "constantly teasing, terrified of self-seriousness, addicted to playful nonsense-sounds" (rumpy-pumpy, naff, cream-crackered). Michael Adams of the University of Indiana insists slang is not a bad copy of standard language but a response to expressive needs the standard language cannot meet.
The day after tomorrow is the third day of the rest of your life.