loose lips 祸从口出；噤声令；口风不紧

【例句】
First of all, they must manage their life, a mouth, loose lips, so much hurt.
人生首先要管好自己的一张嘴，祸从口出，话多伤人。

The details of this project are extremely confidential, so make sure you don't have loose lips about it.
关于项目的详情是要绝对保密的，因此你要保证自己的口风不松。