Perry gives a sexy over-the-shoulder glance before performing in London. Plus: Lady Gaga, Ashlee, Pete & Bronx, Zac Efron and more

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IT'S A HOE-DOWN

Matthew McConaughey trades in his surf board for some gardening tools Saturday during Service Day at Venice High School in Los Angeles. The actor's j.k. livin foundation partnered with several local non-profit organizations for the event, in which students and volunteers painted, landscaped and cleaned up the area around their high school.