Mine isn't very exciting, it's just an abbreviation of my real name. I used to have a unique nick with a thrilling back-story, but abandoned it as the Internet became mainstream and I found myself having to explain and spell it in awkward social situations.
Antti is a very common Finnish male name, but with all the uncertainty and doubt surrounding Stunts scoreboard entries thanks to certain community members, nobody knows if he's real. 
It wouldn't be
Yallis, would it?
What about Duplode, Antti, dstein?
Mine is not too complicated either. Like all of my nicks, it comes from the one "unique" characteristic of my real name:
Daniel
David Mlot Pinheiro
As you can see, it's a double-D name. In fact, "Double D" or just "Double" is my current general-use nickname. Anyway, "double D" becomes "duplo dê" in Portuguese. From there to "Duplode" is a simple step, and that's how my online nick was created long before ZakStunts even existed... the only subtlety is that "Du
plode" is not supposed to be pronounced like "duplo dê" in Portuguese (stress in the "dê"), but rather with stress on the "plo" - so that the connection is not immediately obvious
