OK Rules, OK?
How does an expression of uncertain provenance and contested spelling, for which each language already has its own long-standing version, take over the world? Allan Metcalf, author of OK: The Improbable Story of America’s Greatest Word, has published an introduction on the expression and its spread across the world. With several alternative spellings (okay, o.k. and ok), the term seems to have originated in 1839 as a lame joke published in a newspaper - news that will no doubt only encourage creators of lame jokes the world over. There is no mention of the origin of OK’s less fashionable cousins, okey-dokey and okely-dokely. For what it’s worth, here’s our favourite story of how a word can come into being.
Update: here’s a feature at HuffPost Books on the origins of several other popular terms.