Rihanna’s racy gown

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Rihanna, who turns 24 on Monday, showed off some serious leg over the weekend when she stepped out in a racy floor-length satin gown. Plus, you'll never guess who the "We Found Love" singer has been tweeting! Elsewhere, Taylor Swift and Zac Efron looked ready to star in a remake of "Grease" at the Los Angeles premiere of "Dr. Seuss' The Lorax," while Zooey Deschanel was "adorkable" as usual in a plaid vintage gown at the Writers Guild Awards.