Plus: How Justin Bieber spent Mother's Day, Audrina Patridge, Channing Tatum and more
• Katy Perry threw a party to debut her new single “California Gurls” – and the singer made sure she had her favorite treat with her: red velvet cake. Also there? Her fiancé Russell Brand and close pals who all fêted the new tune – and a friend’s birthday – at Trousdale Lounge in L.A. Nearby, real-life (and virtual) lovebirds Avril Lavigne and Brody Jenner, who hung out with the Hills‘s star’s mom, Linda.
• Justin Bieber spent Mother’s Day shopping at The Grove in West Hollywood with his mom, Pattie. The two also lunched at the Cheesecake Factory, where the pop star arrived holding a skateboard. He ordered a strawberry lemonade and a milkshake and was also “taking tons of photos with his fans,” an onlooker says, adding, “He looked a bit flirtatious with some of the ladies, too.”
• In New York, Channing Tatum took shots with his friends at Fanelli’s Café in SoHo. Sitting near the window with two guys and a girl, the actor laughed the night away, deep in conversation with his pals at the low-key pub. The next day, Tatum was spotted shopping at Rag & Bone in the West Village.
• After a Vegas trip, Audrina Patridge continued her 25th birthday celebration with boyfriend Ryan Cabrera at just-opened L.A. nightspot Las Palmas. The Hills star, who was joined by close friends, sipped tequila and enjoyed a serenade by Cabrera, who played three songs including an acoustic version of Justin Bieber’s “Baby.”
• Winona Ryder, signing the dressing room wall after buying a vintage red scarf, a necklace and scented oil at Sofia, a boutique in Chicago’s Gold Coast neighborhood.
• By PAUL CHI and JENNIFER GARCIA