Mischa Barton Sing 'Oops... I Did It Again'

Mischa Barton gave an impromptu performance of Britney Spears' hit song 'Oops!... I Did It Again' during a night out partying. The former 'O.C.' actress was enjoying an evening out in London on Tuesday (28.11.06) when she decided to treat revellers at the trendy Paper nightclub to some of her singing. Mischa, 20, jumped on stage and launched into the famous track, and even treated clubbers to a