Folkie Joni Mitchell chose an unlikely collaborator for her song "Dancing Clown" - leather-clad rocker Billy Idol.

"I laughed and I was shocked," Idol said, recalling Mitchell's invitation to join her in the studio last year when she was working on the album "Chalk Marks in a Rainstorm."

"I wasn't sure it was the right thing to do. The she read me the lyrics. It was close to what I would sing about."

Things went so well that Mitchell even extended Idol's part in the song, which she describes as "a three-character play" that also features another rocker, Tom Petty.