My usernames have changed periodically over the years. My first one was "Technotate", which my mom thought of (Tater was my unofficial nickname my mom called me, and it ). I liked technology and Tater, not much to go off of. To this day, it's still my original Xbox username, which is yet another reason I hate Xbox, since they only let you change it once before they force you to pay. After that, I started my trend of combining two of my interests/passions/obsessions as my username.
FalloutFlash(21)* - This is definitely one of my favorites. When I began using it, I was really into the Fallout game series and DC's Flash. The "21" part comes from my favorite number (I usually used it, but not always). This one is a little special, but I'll get to that after the next entry.
LuigiLover - I discovered my favorite Mario character was Luigi, and that's about it. I don't know what made me change it, but I did. When I eventually stopped using it, it was because a friend said that he didn't really like it because my previous username was way cooler. So I changed it again, and it was...
FalloutFlash(21)* - So yeah, I couldn't decide on a new nickname, and I already really liked this one, so I just switched back, hence why I said previously that it was special. I kept this one for a good while, before eventually...
OkuuFallout (present)** - Soon after discovering Touhou and deciding that Okuu was my favorite character (at the time), I changed my username to this, which is what I still use to this day. One thing to note is that the "Fallout" portion is there only because I liked it in my previous username so much that I wanted to keep it. It's only a coincidence that it just so happens to fit with Okuu, although that was definitely a reason why I set my mind on it.
*Parentheses indicate that that portion was also used.
**Obviously not a part of the username