Mental Floss

BIG QUESTIONS

Ever wondered why a secret advantage is called an "ace in the hole"? Discover the 19th-century poker origins behind this iconic idiom.

Paul Anthony Jones


The Prague Astronomical Clock, first installed in 1410.

Ever wonder why we say "o'clock"? Discover the medieval origin of the phrase, how mechanical clocks changed timekeeping, and why the contraction stuck.

Nitya Rao






The phrase “pie in the sky” has a surprisingly dark history. Learn how labor activist Joe Hill coined the expression in a song in 1911.

Paul Anthony Jones

Why are basketballs orange? Learn how the familiar color came about and why it replaced the dark brown balls once used in the sport.

Paul Anthony Jones








Why do we say “add insult to injury”? Discover the surprising history behind this common phrase, which dates back to Ancient Rome.

Jane Alexander








Blue postal mailbox standing beside road and green grass

U.S. mailboxes have been many different colors, but blue was adopted surprisingly recently. Here's the story behind the shade.

Jane Alexander

The phrase "put a sock in it" has been telling people to quiet down for more than a century. Here's the most likely story behind the expression.

Chris Wheatley
Fireworks for the feast of Rome's Patron Saints Peter and Paul

Accidents, the search for immortality, and war may have all played roles in the development of these aerial attractions. Here's how the word "fireworks" came to be.

Eden Gordon