My username is based on my real name - first initial, middle initial, first 6 letters of my last name. The university I attended suggested this format when I registered, and I kept the pattern but changed the first and middle initials. Actually, my username here is based on the name I was considering taking before I even found "Anna" (I wonder if I can talk somebody into changing that?)
My display name (Anna++) is a reference to programming. The "++" operator increments a value by 1.
a = 1 # The variable "a" holds the value "1"
a++ # "a" is now "2"
a++ # "a" is now "3"