X-Istence came when I was moving away from an old nickname. At this time I was dubbed the destroyer at my high school, so existence made sense, except I just liked the idea of xistence without the extra E to make it more Internetey and then came off course X-Istence, where X was meant to stand for Extremely and the I for Insensitive, as I really at the time did not care about anyone or anything.
0x58 came along later when friends thought my nickname was too long. 0x58 is uppercase X in the ascii table. Later I have been known as x58 or just 58. 0x58 also came in handy for the hacker community as the lower the character count in the nickname, the cooler you are 😛.
After watching Idiocracy I was also dubbed BeefSupreme by my professor who is also a very good friend. Shortened to Beef over the phone and in person, so it tends to confuse people. "What's up beef?" *people look around the room in confusion* "Nothing, what's up LosT?".
Nyt_Muves from another forum, the brother of the professor nicknamed LosT, also tends to call me Untgrad (Idiocracy as well) since the main character in the movie asks:
"Upgraydd, that sounds Dutch, I once knew a Dutch guy, his name was Untgrad"
I go by many nicknames, and I don't mind. It is interesting to me, and keeps certain parts of my identify undisclosed with certain people, or lets me have two entirely different "faces" when talking to people.