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.
The fabled event in when someone is so damn horny and full of lust for someone, something, or perhaps both, that the sheer lust alone causes them to bust one, no stroking, no gripping, no touching, nothing, the sheer raw lust is all that acts in this mystical scenario.
Dude, that was the sexiest microwave I ever saw, I literally hit the lust and bust in the Wal-Mart.