Episode 3X5158 THE GRANDFATHER: PART II
Olivia (recurring guest star HILARY DUFF) says something she regrets during an appearance on a talk show with host JIMMY FALLON (guest starring as himself) and tries to keep Dan from finding out. With election day around the corner, Nate suspects his grandfather (recurring guest star JAMES NAUGHTON) will stop at nothing to get Tripp (recurring guest star AARON TVEIT) elected to Congress. In the midst of another feud with Serena, Blair befriends a new It girl. In an effort to make Serena jealous, Blair takes her new friend to an election night party at Chuck's hotel.