Mine is an interesting and long story.
Back in the fourth grade, I played this game called "Gunbound"
My screen name in the game was gmmack2000.
My initials are GM. My nickname is mack. I just tacked on the 2000 for fun.
Then gunbound banned my account because they came out with a new policy, you cannot have "gm" in your screen name because you might be impersonating a game master (gm). So, I got a new account with the screen name "gbmack2000."
gb stood for Gunbound, and mack was my nickname.
I took off the 2000 because it became tedious.
So, now we have "gbmack."
The game gunbound was the first "thing" i did online. Therefore, it was the first thing I registered for online. Whenever I registered for any website or game online, I used "gbmack" because I got used to it.
I've never had another username.