Illusion Of Asymmetric Insight
The illusion of asymmetric insight is the somewhat egotistical and even narcissistic belief that you know more about others than they know about you. This happens partially as a result of the normal human reticence to speak about themselves, as well as the desire to know "everything" about everybody else. Most people don't go about expounding on what they actually know or understand about people they know, leaving questions about how much they actually know about other people. An example of this could be the shock that you feel when you see someone you think you know (like a teacher) in a social environment (like a party) and you realize that you don't know them as well as think you do.