English Help Online's Blog

Today, I’d like to write about another idiom: to have a big mouth. This means for a person to be unable to keep a secret. We usually use this expression when talking about other people, but we don’t usually say this about ourselves. If you say it directly to another person, it’s very strong and not so polite. For example:

My sister told everyone about my promotion before I could do it! She has such a big mouth!

Don’t tell Martin about Jane’s surprise party! He’s got a really big mouth, and he’ll probably tell her.

I can’t believe you told my parents that we were drinking beer last night! You have such a big mouth!

As you can see in the examples, we often emphasize this expression with “such a” or “really”. If we simply say something like, “He has a big mouth”,  it sounds rather weak and a little unnatural.