Katy Perry was high when she recorded "California Gurls."

The singer was overcome by the weed smoked by her collaborator Snoop Dogg [currently going by the name Snoopzilla], when they recorded a rap in the middle section of the song, for her last album Teenage Dream.

"It was really cool. He came by the studio, played the song and rolled a J. Everybody was contact [passively] high. But he was super-cool and he's been around forever. It's really amazing if you meet someone that's been around for 20 to 25 years and they're still cool, because sometimes they aren't," Katy is quoted by The Sun newspaper as saying.

The first song Katy wrote for her latest album, Prism, was "By the Grace of God," which has a much darker tone, as it was inspired by Katy's breakup with ex-husband Russell Brand, and she admits she was in a bad way when she wrote it.

"I was in bed for about two weeks. I was pretty f***ed ... it hurt a lot - I got a good knock ... The song is very autobiographical, I was down and out, I'd lost hope, all of my self confidence had been shattered ... My self-worth was in someone else's hands, which is never a good idea, because it can be taken away from you at any time. And it was, and I was shattered," she said.

Prism is set for release tomorrow.