Do you know where the term "OK" originated?
It turns out the initials "O.K." originally stood for the misspelled phrase "oll correct," a popular slang expression for "all correct" that was written incorrectly on purpose.
Apparently, during the 1830s it was a bit of a fad for students in the United States to misspell words and then use their abbreviations when talking to each other. Much like today's mobile phone text messaging abbreviations, young people thought it was cool to use these expressions. They liked abbreviations like "KY" for "no use" ("know yuse") or "KG" for "no go" ("know go").
According to History.com, the term "OK" became widespread when the Boston Morning Post printed it in an article on March 23rd, 1839. Once in the newspaper, it gained popularity with political figures of the time. The term stuck. Today, "OK " is recognized just about anywhere in the world.
If you'd like to read more about the story of those two letters, see the full article on History.com here.