Opened your mouth - Idioms by The Free Dictionary
open (one's) mouth (redirected from opened your mouth)
open (one's) mouth
To say something, especially that which is indiscreet, boorish, or meant to be a secret. Why did you have to open your mouth about my crush on Tommy? Why couldn't you just keep it between us? You've got to make sure that he never opens his mouth about what went on here today.
open your (big) ˈmouth (informal) say something when you should not: Why do you always have to open your big mouth? Can’t you just keep quiet sometimes?
References in periodicals archive
Their whole lives were turned over to getting tickets to hear you sing, to standing in their seats and the aisles, screaming and crying every time you opened your mouth