This riddle asks: What can you keep only if you never share it? At first, it sounds like the answer might be some valuable object, but the trick is that it is something you keep by not revealing it.
The answer is: a secret.
A secret stays a secret only while it remains private. The moment you share it with someone else, you are no longer the only person keeping it, and the information may spread even further.
The riddle works because the word “keep” can mean more than physically holding onto something. Here, it means keeping information confidential.
It is a short, familiar riddle with a simple answer, but the wording makes you stop and think because “keeping” and “sharing” usually sound like actions involving an object.
