Barry Brecheisen/ GettyImages.com KISS ME, KATY: Katy Perry, performing "I Kissed a Girl, "Hot and Cold" and "Ur So Gay" during Lollapalooza at the Underground's Motorokr Lounge in Chicago.
FATHER'S DAY: Jerry O'Connell, being congratulated by friends on his impending fatherhood while hanging out at talent manager Fisher Pence's birthday party at a private home in the Hollywood Hills.
URTH DAY: Sarah Silverman, waiting in line to place her order at the Urth Caffé on Melrose Avenue in West Hollywood.
SUMMER CAMP: Ozzy Osbourne, performing with Camp Freddy, for the ESPN X Games party at the House of Blues in Hollywood.
DOGHOUSE: Aubrey O'Day, carrying her dog, Ginger, while walking in the Alice + Olivia fashion show at the EMM Group Estate in Sag Harbor, N.Y. She later sipped some Perrier-Jouët champagne poolside with Emmy Rossum.
BOOTLEGGED: Allison Janney, picking up a pair of Keaton 116 boot-cut jeans at Earnest Sewn Co.'s flagship store in New York's Meatpacking District.
BURNT TOAST: American Idol runner-up Katharine McPhee, having lunch with hubby Nick Cokas and friends at Toast in West Hollywood.
MESSING AROUND: Debra Messing, dressed down while dining with her son at California Pizza Kitchen in Westwood.
FIVE-PACK: Former Party of Five hottie Scott Wolf, running on a treadmill after weight training at L.A. Fitness in Los Angeles.
—Additional reporting by Alexis Brunswick