big mouth, have a

have a big mouth

To have a tendency or habit of speaking incessantly, indiscreetly, and/or in a noisy, boorish manner. I can't stand Terry's new husband, he has such a big mouth! It's like no one else gets a chance to speak when he's here. If I'd known you had such a big mouth, I'd have never shared my secret with you!
See also: big, have, mouth
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

big mouth, have a

Also, have or be a loud mouth . Be loquacious, often noisily or boastfully; be tactless or reveal secrets. For example, After a few drinks, Dick turns into a loud mouth about his accomplishments, or Don't tell Peggy anything confidential; she's known for having a big mouth. [Slang; late 1800s]
See also: big, have
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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