A Melded mixture of death growls, false vocal / vocal fry screams, bee-boxing, scatting, and only what can be described as deranged humming. Invented and popularized by Jonathan Davis of the band Korn. Korn has many examples of of the Demon-Scat, but perhaps the most notable examples are from songs like "Twist," "Ball Tongue," "BBK," and of course, "Freak on a Leash."
Me: "Uh-oh. Here comes Jonathan Demon-Scatting again!"
Jonathan: "Boom! Dup buh Boom! Damah eemah! Da-Boom dup buh doom ahmah deemah oh! Boom Doo dup buh boom dahmah deemah! Da Boom dup buh boom dup ah LET IT GO!"