Kim Kardashian, Kelly OsbourneJon Kopaloff/FilmMagic

Kim Kardashian and Kelly Osbourne buddied up at a charity bash thrown by the St. Bernard Project in Los Angeles last night. Britney Spears headlined the event, which was organized to raise money for efforts to rebuild New Orleans—a cause close to the Louisiana native’s heart. Osbourne blasted some Britney in the car ride over to get herself pumped for the party. “Listening to @britneyspears in the car on the way there!!!!” Osbourne tweeted. Click “See the Photos” for more photos from last night’s hottest parties, including pics of Penelope Cruz, Zac Efron, Nicki Minaj, Jennifer Hudson and more.