Mad Bullet Bills are enemies in the game Super Princess Peach. They are obviously just angry Bullet Bills. They have hideous glares on their faces, and are surrounded by fire. More dangerous than normal Bullet Bills, they fly incredibly fast. The cannons they are shot from are not seen, and they only appear in the levels that are unlockable only after defeating Bowser for the first time.
They are probably related to Mad Banzai Bills.