Katy Perry and Rihanna are shown backstage after attending ‘Ka’ by Cirque de Soleil at the MGM Hotel  in Las Vegas on September 18th, 2010.  Rihanna also hosted a Bachelorette Party for Katy on this same night.  No matter how sane or sober you are, when you watch Cirque de Soleil, you really still feel like you are tripping.  The girls look like they were cracking up during their backstage tour.  Fun Times.