Whose ass cheeks took a breather out in London this weekend?

As she was mobbed by fans and paparazzi while leaving London's Cirque du Soir club in London on Saturday night, Katy Perry looked either a little too tipsy or a little too overwhelmed with the crowd as she was guided to her waiting vehicle. In the melee, Perry's skirt rode up high and gave all the slavering masses a glimpse at her hind quarters, perhaps enticing a few to pay special attention to which brand of underwear she had on. While in London, Parry was asked by a local radio station if she had any plans to collaborate with her good friend and fellow pop singer Rihanna to which Perry replied no music plans were in the works, "but we're going to have sex!" Now to figure out which will be the S and which will be the M.

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