"Katy Perry feat. The Black Eyed Peas, Khaleel Deal, Rihanna, Ne-Yo, Jason DeRülo & Lady GaGa vs. Dr. Alban - Last Friday Night (We Sang Hallelujah) (S.I.R. Remix)"


http://www.youtube.com/watch?v=KfGI7DqyT4U

Acapellas:
Katy Perry - Last Friday Night
The Black Eyed Peas - I gotta Feeling
Khaleel Deal - Only Girl (In the World)
Rihanna - Only Girl (In the World)
Ne-Yo - Closer
Jason Derülo - Don't wanna go home
Lady GaGa feat. Colby O'Donis - Just Dance

Instrumental: "Sing Hallelujah" by Dr. Alban

Link: http://www.myspace.com/sirremixes/blog/543521303