From the movie Road Trip, where Tom Green's character is trying to get a snake to eat a mouse, and wants to revel in it's demise. He gets more and more upset until he starts screaming "MITCH!!! UNLEASH THE FURY!!"
The process by which a person, usually driven by emotional or personal reasoning throws all thought out of the window and performs a rash act. Fighting, selling stock in a panic, blowing your credit card on meaningless junk or bidding on ebay often result.
"Man, this guy told Phil he thought he was gay, then Phil unleashed the fury on him - we had to call an ambulance"
"If Anna doesn't stop bugging me I'm gonna unleash the fury"