On Tuesday night, Project Runway Season Four winner Christian Siriano celebrated his 23rd birthday. But he didn't have to plan anything; it was a surprise! The place was Citrine in New York City. The fabulous guest list included Leigh Lezark, who was also the night's DJ, actress Leven Rambin, and American's Next Top Model alum Kim Stolz. An interesting mix, right? That about sums up the adorably charismatic Christian. From the looks of it, the birthday boy had a blast and then some. Posing with his birthday cupcakes, clapping, kissing his guests — yeah, that sounds like Christian. Welcome to the party.