You may want to grow thicker skin. People joke about all kinds of inappropriate things in private. It's often a bonding experience. If I were to tell you something that I don't necessarily mean, but would harm my reputation if it were to get out, it's a form of a secret. If you reciprocate, often we would feel closer.

There are a lot of reasons to get upset in this world, and a lot of things to get upset at. If this is something sensitive to you for personal reasons, I get it. Otherwise, you should probably just accept that people aren't going to always conform to your view of perfection.

I joke all the time with my family and friends that I'll kill them if they ever repeat something I say in confidence. It's tongue in cheek, an obvious over-exaggeration, and often used for humor.