Is a collaboration between Katy Perry and Taylor Swift happening? In a new interview on Monday (May 11), Perry teased the possibility while promoting her upcoming performance on American Idol."Well, you're just gonna have to tune in to Idol next week to see all rumors, true or false," the pop star told Extra as her fellow judges Luke Bryan and Lionel Richie laughed along at her promoting the show.Whether or not it's a collaboration with Swift, Perry is set to release her new track "Daisies" --