spill the beans

To reveal something that was meant to be a secret
把本应该作为秘密保守的事情揭露出来

If you spill the beans, we'll be in trouble.
如果你不慎说漏了嘴，我们都会有麻烦的。

You can't trust him to keep a secret, he is sure to spill the beans before long.
切勿相信他会保守秘密，过不多久，他肯定会泄露于人的。