Write about one thing you’ve never told anyone and explain why

This is a suggestion from The Daily Challenge Blog at WordPress

I don't think I have anything that I have never told anyone. I am a very open person and keep very few (if any secrets). I don't spill my whole life to everyone I meet and can be quite private, if that makes sense, but I do talk to those that are close to me. I am selective about who I tell certain things to but not secretive.

Do you find that you have different friends that you tell different things to?