Your sister told you something private — a worry, a secret, something she trusted only you with. "Don't tell anyone," she said, and you promised. It felt good to be the one she trusted. Then, days later, you were with a couple of friends, and the secret just... came out. It made you interesting for a minute. It was good gossip. You saw the flicker of "ooh, really?" on their faces and it felt great — right up until you remembered whose secret it was, and the promise you'd made, and the fact that your sister had no idea you'd just handed her private worry to people she barely knows.