Definition
To talk excessively in a loud and unrestrained manner; to speak without thinking or consideration.
信口開河
He always likes to shoot his mouth off about other people's ideas during meetings.
他總喜歡在會議上對別人的想法大放厥詞。
Don't go shooting your mouth off to the media, you'll get yourself into trouble.
不要對媒體亂說話，你會給自己惹麻煩的。
She has a habit of shooting her mouth off before she even understands the situation.
她有個習慣，在還沒了解情況之前就亂說話。