With her pooch in tow, the Gossip Girl star celebrates her 21st b-day on the New York City set of her show. Plus: Ashlee Simpson, Lindsay Lohan, Paris Hilton and more
Credit: Eric Charbonneau/WireImage
Published: Monday Aug 25, 2008 | 05:50 PM EDT
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On hand to show their high school spirit, Ashley Tisdale and Zac Efron share a hug before getting pumped up at Disney's High School Musical 3: Senior Year Ultimate Fan Pep Rally at the El Capitan Theatre in Hollywood on Saturday.
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