大嘴巴

別告訴她，她是個大嘴巴，會到處亂說。

Don't tell her, she's a big mouth and will spread it everywhere.

我不小心當了大嘴巴，把祕密說出去了。

I accidentally became a blabbermouth and revealed the secret.

他是出了名的大嘴巴，什麼事都瞞不住。

He's a notorious big mouth, he can't keep anything secret.