Disney darling Demi Lovato kickstarted her 18th birthday celebrations with ex-boyfriend Joe Jonas at a surprise premiere concert on Wednesday night (18Aug10).
The actress/singer, who turns 18 on Friday (20Aug10), surprised celebrities and fans by taking to the stage with the Jonas Brothers and the cast of Camp Rock 2: The Final Jam after the screening in New York.
Wearing a summer dress and a denim jacket, Lovato performed It's On with her co-stars.
She'll spend her birthday planning her next concert with the Jonas Brothers on the Camp Rock 2 soundtrack tour.
The film will debut on the Disney Channel in America at the beginning of next month (Sep10).