English Idiom: (Keep something) on the down low
There are some things that you do not tell everybody; you keep them secret. In other words, you keep them on the down low.
Perhaps you are eating too many doughnuts. That is something you may not want your doctor to know about even though what she doesn’t know may hurt you.
Maybe your friend has told you that she is having an affair with her assistant. You should keep that tidbit on the down low too.
Some things should be kept secret and not shared publicly; therefore, you keep them to yourself and guard the secret.
