LOL I WAS SO FOCUSED ON TSUNA BITCHING ABOUT UGLY PEOPLE CARING ABOUT HIS WELL-BEING THAT I TOTALLY MISSED THAT.

It sounds like a random nickname given to him because he is scary and can apparently pitch baseballs into neighboring dimensions to me, but then again, this is a manga known for its extremely literal nicknames (SMOKIN' BOMB), so hmm. If there is someone else in the series who fights using dynamite, it could get interesting.