2.) Mentally ill, or simply retarded.
3.) To be displeased with something.
4.) A word used to emphasize the word that comes directly after it or two words before it, similar to the common English word "very".
5.) A word that suggests something was "cool".
2.) Stay away from that trouble maker, Johny, he's a mad nigger.
3.) Oh shit that nigga so mad he got his ride jacked.
4.) shit baby that ride was mad good - or - Dam bitch that ride was wack like mad.
5.) Dzayum, her titties be MAD.
For the most part, it means angry.
She has mad problems.
A MAD Movie is a Japanese fan-made video, much like an anime music video (AMV), that generally originate from the Japanese website Nico Nico Douga. MAD can also describe the Japanese AMV community, although they can be anything from audio clips, edited pictures, to wholly original creations. MADs do not necessarily even need to be related to anime, though the more popular ones typically are. The term MAD (occasionally M@D) is thought to be a reference to the name of one of the original MADs, rather than a particular acronym for anything.