A name for a nasty ass creature who may be lurking in your closet at this very moment. Often dangerous to encounter and not safe to touch, will run, bite, and then bite again in that order. Will tire out quickly and begin to cry about being tired, but it's cool because now it's not a threat, just your problem now.
Bro, I went to get my sweater and there was a whole-ass madsun in my closet.