Girls know the best place for a good goss session is in the ladies room. So, we can only imagine that the toilet at the 2011 Costume Institute Gala was the bathroom to be in last night. Luckily, Livia Firth, wife of Oscar-winner Colin Firth, was on hand to document just how fabulous a restroom can be, whipping out her phone to snap some pics that she naturally shared with the world via Twitter. Though she didn't go inside any stalls, she managed to shoot Rihanna (above, left) posing in her sexy Stella McCartney dress, with Salma Hayek hiding behind that enviable posterior. Also in her cellie's lense? Fashion journalist Hilary Alexander, Stella McCartney herself, Lauren Hutton and Yoko Ono (above, left), the latter two who chanced NYC's anti-smoking laws and, in true high school style, sneaked a ciggie in the bathroom. We wonder if they knew Livia was Tweeting...