Considering that she once celebrated her birthday by hosting parties in five different cities, Paris Hilton has set the bar pretty high when it comes to self-indulgent birthday parties. So when it came time to celebrate her 27th birthday, she did what every slutty heiress would do — take the stage with The Pussycat Dolls in hooker clothes, of course! But while Hilton played quick change artist (alternating between a "sexy" cop and a a "sexy" lingerie model), there was one newly sober and newly naked star who wasn't allowed to attend the festivities.