09/16/2010 AT 12:00 PM EDT
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.