Wanted Chris Brown duet because he is dirty: Rihanna

London: R&B singer Rihanna wanted to duet with ex-boyfriend Chris Brown on her hit single `Birthday Cake` because she feels he is dirty and shocking. The 24-year-old`s collaboration with Brown, who was convicted of assaulting her three years ago, on the song had been criticised widely by her fans, reported Contactmusic. "I thought it would be cute to do it with a guy. I wondered, who can be dirty, someone who people will really believe," she said. But the brunette beauty insists her fans are keen for she and Brown to collaborate again, as they have made peace since 2009`s altercation. "Look, I understand that people had every right to be concerned about it. But I didn`t see it that way because I`m in a different place. Music is music and my fans have been asking me to record with him. I just felt like it was time. It was time," she added. PTI