(Photo Credit: John McMurtrie)

Hollywood Undead weren't the first rap-rockers to don masks, shroud themselves in mystery, and frighten small children: First there was Slipknot.

The nine-piece band from Des Moines, Iowa is known for their creepy, horror-movie-inspired masks as well as their hard rock and metal sensibilities infused with the occasional rhyme and melody.

And remember when Slipknot and the Jonas Brothers were both on FNMTV? Wasn't that weird? Yes. Because it totally was. Want more weird? Watch Slipknot's new video, "Sulfur," which just premiered on MTV's Headbangers Blog. Too scary? Jonas cookie.