What is Katy Perry’s Favorite Song? [VIDEO]

Apparently, Katy Perry is addicted to Tegan and Sara's Closer. Don't believe me? I've got proof!  At least she was addicted in January. Seems a lot of people are into Tegan and Sara. They're approaching 300K followers on Twitter and 1M likes on Facebook. They've got a new album in stores called Heartthrob and it's available now on iTunes. It's their 7th studio album AND they're on the road with Fun. These identical twins hail from Calgary, Alberta and recorded their first two albums in their school's recording studio. Both sisters are openly gay and support marriage equality.