"The Raving Rabbid series is based around Rabbids, a species of maniacal anthropomorphic rabbits that serve as the primary antagonists. Their most well known traits feature various slapstick comedy elements; running around wielding various household objects, dressing up as various other fictional characters, and most of all, constant screaming. Although essentially the "villain" in the game, they have gained a considerable popularity and fanbase through viral videos and media appearances. Many people even suspect them to overshadow Rayman, despite hints that there could be a Rayman 4.
The Rabbids appear as humanoid, stout, usually white lagomorphs with big round eyes and a large mouth with two large incisors. Rabbids tend to be somewhat mentally unstable, and often experience strange adrenaline rushes, where their eyes turn red and they emit a loud yell: DAAAAAAAAH! (although spelled "BWAAAAAAAH!") Other than this, their only communication seems to be random gibberish. This is also often a precursor of the bunny smashing something or attacking someone with its tool of choice, usually a toilet plunger or something plunger-related, such as a plunger-shooter, or other household items, such as feather dusters, ladles, toilet brushes, toy shovels, tennis rackets, sausages and other objects. Rabbids also have a penchant for dressing up. These outfits include French maid outfits, snorkels with duck-shaped swim rings, ninja suits, pirate outfits, and various other pop culture costumes."
Source: Wikipedia, "Rayman", available under the CC-BY-SA License.