White Line Fever
An Australian term to describe the radical change in a person's behavior when they start playing sports, aka stepping over the 'white line'. The radical change can result in a normally mild mannered individual, becoming aggressive, loud and extremely competitive maybe even violent during gameplay, once the game is over they go back to their usual mild mannered self.
Example:
"Bruce isn't one to start a fight, but once the whistle's blown he gets white line fever and who knows what'll happen."
"Bruce isn't one to start a fight, but once the whistle's blown he gets white line fever and who knows what'll happen."