Sides to a person

I can always tell when I'm really comfortable with someone.  I blurt out the first thing that comes to mind, even if it is embarrassing or silly, and I laugh so hard I cry.  That's how I know I trust the person with the real me.  No masks.  No careful editing.  But sometimes, for one reason or another, I feel that I have to show only certain sides of me.  For example, there's a guy I work with, and although we're friends, he has never seen the real me.  I'm very careful not to be too vocal about my political or religious thoughts.  [He's the complete opposite with no room for discussion.]  I'm very careful not to divulge items I intend to purchase [as they tend to show up on my desk.]  I'm a toned-down diluted version of me.  And while he thinks we're such good friends, I know that it's all a half-truth.  But I do it because it's what I want.