S2, E20: Serena decides to throw Jenny an intimate party for her sixteenth birthday, but things get way out of control when Poppy Lifton (recurring guest star Tamara Feldman) turns the small gathering into a huge social event. In a moment of weakness, Vanessa agrees to help Chuck with a scheme having to do with Blair and Nate. Meanwhile, Rufus learns that Dan will not receive financial aid at Yale and tries to figure out another way to cover the cost of his education. Recurring guest star Armie Hammer ("Reaper") appears as Poppy's boyfriend, Gabriel.