First Names
I used to have a problem calling people by first names when I was younger. However, I think it was, at least in part, a result of my feelings of inferiority from years of being bullied. In a sense, I did not feel worthy to call people by their last names. Now, I call virtually everyone by their first names, including the president of the college where I am a professor. (All faculty and administrators are on a first-name basis where I work.)