By People Staff
September 16, 2010 12:00 PM
Gilbert Carrasquillo/FilmMagic

Kelly Osbourne jumped into a hot tub fully clothed and bounced a beach ball with her male friends (who were just wearing underwear) while partying at Le Bain inside New York’s Standard Hotel. The starlet was there earlier to celebrate at the V magazine bash at the Boom Boom Room, also at the Standard. Meanwhile, Mary-Kate Olsen was dancing nearby and strolling the room in a leopard-print jumpsuit.