Q: Hi, my grandma has a quick question for you: Why do people say “I’m all in” when they are tired? Thank you so much.
A: According to Partridge’s Dictionary of Slang and Unconventional English, the term “all in” is a colloquial expression that originated on the floors of stock exchanges in the mid-19th century. If the market was “all in,” it was down or depressed; if it was “all out,” it was rising or inflated. By extension, the term “all in” was borrowed in the early 20th century to mean “exhausted” or “used up” in reference to people or animals who were verging on collapse.
The Random House Historical Dictionary of American Slang has a somewhat different explanation: “all in” originated at the card table. If you were “all in,” you were broke (that is, out of money), because you had already put all of your money in the pot. So you couldn’t play anymore.
There may be some truth in both explanations. The poker-playing term could easily be applied to the stock market, if investors were played out and no longer putting money into the kitty. Hope this sheds some light!