The way the school system in my area worked is that five elementary schools fed into one middle school. I have the third most common surname in the country, and the fifth most common given name for girls. So when I got to my first day of 7th grade, it turned out that there were SIX girls with my same first and last name. Nicknames were demanded, if for no other reason than to differentiate. I had recently been introduced to RPGs, and my first character's name was Aris. So I became Aris. It stuck, to the point where many of my friends actually have to stop and think for a moment to remember my real name.
The only other nickname of significance was in college, where my roommate at the time called me Elf. Our computers were in the same room of the apartment, yet I could wake up, leave my room (opening and closing doors), walk across the apartment to the computer room, sit down in my chair, and only the sound of my computer booting up or me clicking at the mouse would alert her that I was there. So theorized that I had to have a racial bonus to Sneak.
