I think about that all the time. Usually the answer is, "Yeah, but not 100% about EVERYTHING." There's usually only one or two things that I wouldn't feel comfortable talking about with, with basically everyone I know. And that does not mean I don't feel comfortable talking about the SUBJECT; it means I don't feel comfortable talking about the subject with THAT PERSON.
The only other thing I can think of that would have me say "Yes 100%" is if I am having an intellectual conversation with one or more individuals who are on the same intellectual level, so to speak. We are able to freely without having to worry about whether or not the other parties will understand. Usually that's about music, religion, movies, etc. etc. It's much more freeing compared to all of the idiots that I deal with on a daily basis.