Janet Mayer/Splash News Online
01/25/2010 at 03:00 PM EST
After taking a bow at New York's Radio City Music Hall following a sold-out four-night stand, Lady Gaga
hightailed it to 1 Oak in the meatpacking district to celebrate. The pop diva wasn't suffering from a lack of energy: At one point, she shook up a bottle of champagne, held it at crotch level and sprayed the crowd, so even her date – designer Marc Jacobs – got doused! Sporting a skimpy black dress and shades, Gaga also chatted up the occasional fan and rocked out to the '80s tracks playing (as well as her own hits!) before calling it a night with her pals just before 3 a.m.
It was a who's who of Hollywood at Paul Haggis's L.A. home, where the Crash
director hosted a backyard brunch to support Haiti relief efforts. Nicole Kidman
and hubby Keith Urban
mingled with guests like Charlize Theron
, who was spotted chatting with rapper Ludacris
. Nearby, Penélope Cruz
and beau Javier Bardem
hung out with Josh Brolin
. In addition to an Asian-inspired breakfast sandwich with miso eggs and fried pork belly, guests enjoyed mini-French toasts, drinks and musical performances by Sheryl Crow
and Jackson Brown
, among others. Overall, the event raised $2.5 million for Artists for Peace and Justice.
, greeting each of her friends with a hug while hanging out in the living room at West Hollywood's Chateau Marmont. One of her pals brought along a toddler, and Diaz turned on the maternal charm, holding the little boy in her lap, an onlooker says. Still, it was a grown-up night out as the actress sipped red wine and chatted with her friends.
hosted a "Waking Up in Vegas" bash at Haze, a new Sin City nightspot inside Aria Resort and Casino. The singer treated partygoers, including Mickey Rourke
, to an impromptu live performance of her hits, and was also joined onstage by Cobra Starship's Gabe Saporta
. But Perry was happy to party, dancing and laughing with her friends into the wee hours of the morning.
Also in Las Vegas: Lauren Conrad
, who celebrated her 24th birthday at the Bank nightclub inside the Bellagio with some girlfriends.
By DAVID CAPLAN, JENNIFER GARCIA and JESSICA HERNDONMonday's Couples Watch >