1. Just between you and me. 就咱俩知道哈。
2. Please keep it a secret. 请保守秘密。
3. Don't let it go around. 别把这事张扬出去。
4. You'd better keep quiet about it. 你最好保守秘密不要声张。
5. Keep it to yourself. 你自己知道就好了。
6. Don't tell anybody. 别告诉任何人。