07/21/2011 at 04:00 PM EDT
danced the night away at her favorite New York club Greenhouse – immediately after performing
at Nassau Coliseum in Long Island. She arrived with her dancers and friends and took over the entire VIP area, sipped Courvoisier Rose and let loose on the dancefloor until 4 a.m. "She was in a great mood and having fun," an onlooker says. The crowd was excited to see her, too, and cheered whenever she faced them.
was quite the doting uncle during a family dinner at Kittichai in New York with his brother, Neil, his sister-in-law and their baby. The relaxed group took over a corner table, but Lambert was especially focused on his nephew, entertaining him throughout the meal. Says an onlooker: "It was really sweet."
Horrible Bosses star Jason Bateman
made a mid-day run to Petco in Beverly Hills for a few bags of dog treats. The actor kept a low-key demeanor, with his head down and sunglasses on as he inspected his purchase while waiting in a very long line. "Few people noticed him," says an onlooker, "but mostly because everyone was paying attention to a puppy at the back of the line."
has been soaking up the South Florida sun
and was ready to party at the launch of Skintimate Cans by Mara Hoffman inside the W South Beach. The reality starlet and a girlfriend snuck in a pizza dinner before heading to Wet Lounge to party in a private, poolside cabana and watch a synchronized swimming performance.
By REAGAN ALEXANDER, PAUL CHI and JENNIFER GARCIA