口くちを出だす

expression, godan verb (-su)

interrupt; meddle; butt in

Used when someone speaks up or interferes in a matter that is not their concern, often with a negative connotation.

• 人ひとの話はなしに口くちを出だすな。

  Don't interrupt other people's conversations.

• 彼かれはいつも私わたしの仕