The phrase "fly off the handle" means to suddenly become very angry or lose control of one’s temper. Its vivid imagery comes from an axe head flying off its handle, which could happen if the tool was poorly made or not properly secured.

The expression likely originated in 19th-century America. Just as an axe head detaches suddenly and violently, a person can “fly off the handle” in a burst of anger.

The first recorded use dates to 1843, when American humorist Thomas C. Haliburton wrote in The Attaché; or, Sam Slick in England: “He flies right off the handle for nothing.”