A.K.A. See-Kay-Why. Band consisting of Deron Miller, Chad Ginsburg, Vern Zaborowski, and Jess Margera. Started in Pennsylvania with Jess and Deron, who called their band "Oil". Changed their name to "Foreign Objects" in 1998, and then, after meeting Chad Ginsburg, called themselves CKY. Bam Margera, Jess' brother, decided to name his skate/stunt videos after the band.
Albums include CKY Vol. 1, CKY Vol. 2, and CKY: Infiltrate-Destroy-Rebuild.
cKy are also 4 movies started being made around 1999 with Bam Margera, Brandon DiCamillo, Ryan Dunn, Raab Himself, and more. It started Jackass, and about half the stuff you saw on the Jackass TV Series was pulled from one of the cKy videos.
Camp Kill Yourself is some of the funniest stuff I have ever seen.