The phrase 'Cry Wolf' is used to indicate that someone is exaggerating or raising a false alarm.
Example of Use: “Don’t pay attention to Peter; he’s only crying wolf.”
The origin of the expression 'cry wolf' comes from one of Aesop’s Fables, The Boy Who Cried Wolf. In the story, a young shepherd amuses himself by calling for help, saying a wolf is threatening his flock when nothing is really happening. He cries wolf so often that when a wolf actually menaces the flock, no one comes to help.