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。