This idiom refers to raising false alarms or exaggerating dangers so often that people stop believing you when a real threat emerges. It warns against losing credibility through dishonesty or overreaction, drawing from the fable of a boy who repeatedly tricks others. The phrase is used in contexts of warnings, complaints, or attention-seeking, often with a cautionary or critical tone, emphasizing the consequences of eroding trust.

The phrase comes from Aesop’s fable *The Boy Who Cried Wolf* (6th century BCE), where a shepherd boy falsely cries ‘wolf’ to trick villagers, only to be ignored when a real wolf attacks. The fable was translated into English by the 15th century, and the phrase appeared in John Gower’s 1390 *Confessio Amantis*: ‘He crieth wolf.’ By the 17th century, it was a common proverb, as seen in Francis Bacon’s essays. Its use grew in the 19th century, with Charles Dickens and others using it to critique false alarms, and it remains a powerful metaphor for credibility in modern English, especially in media and politics.