Foaming at the Mouth

You use the expression ‘Foaming at the Mouth’ to indicate that someone is making a
furious display of anger or rage.

Example of use: “The boss is foaming at the mouth over Bill losing that account. I wouldn’t go in his office if I were you.”

 

Interesting fact

The origin of the phrase ‘foaming at the mouth’ comes from the appearance of animals afflicted with rabies, in which they literally foam at the moth while in a blind stupor that can include attacks that look like they stem from anger or rage.