Quoted from o-din:

When I was a kid a brand new Bally Fireball machine showed up at the local bowling alley and it was the most awesomeness in a pinball game I had ever seen. I mean demons and multiball? Just what a ten year old pinball enthusiast is looking for.
And I played it whenever I could afford it, but people weren't just dropping dimes on the ground like they do pennies today. Occasionally there would be some locked balls to steal or maybe a replay left on it, but rarely.
So when I joined up I wanted to be Odin in honor of that game, but it was already taken, so I went with o-din instead.

Quoted from Mr_Tantrum:

Well, even though I am red-headed and had a short fuse in my younger years, my name is not about throwing tamtrums in the traditional sense. It is, however, the name of the trick in wakeboarding for a heel side backflip. In 2000, I was working on this trick when my left binding came off and the board did a 360 with my right foot still in it. The result was a spiral fracture of the lower tibia, a spiral fracture of the upper fibula, and a pulmonary embolism nearly resulting in death.
Anyway, after getting home from the hospital and lying around for days, I started playing online Yahoo games (mainly Spades). I needed a screen name, and “Mr. Tantrum” came to mind as homage to this time in my life.