Rihanna is getting the Purple treatment. Prince and his New Power Generation band gave a special treat to concertgoers at Monday night’s gig at Oakland’s Oracle Arena. The music icon slipped a cover of Rihanna’s “Rude Boy” into his set, allowing the female singers to handle vocal duties with Sheila E. on the drums, but he took over at the end as everyone from fans to security guards boogied in the aisles. Watch Prince and company catch island fever.