Katy Perry on the cover of Cosmo Australia!

Katy Perry is being featured in the October issue of Australian Cosmopolitan. She was asked who she would most like to duet with. Katy had to choose between: Rihanna, John Mayer, Drake and Pink. Though Katy and Rihanna seem to be BFF's Katy actually chose John Mayer because she thinks he's a "fantastic songwriter."