Well, I'm used to monikers like "Phantom" and "raven".. not "Thumper" or "bunny"..
I've still got a pair of my Marine Corps coveralls with a "Thumper" nametag. In my case, it came from my propensity to hit things when frustrated. The door of my locker was dented in a full 2" at one point. Needed to pound it back out with a hammer to get it to latch correctly. Tossed a 2" wrench the full length of a hanger once. Boy, did that make a lot of noise when it landed in and amongst all the engine shipping cans.