Michael says that he and Seth were waiting in line for the new Star Wars movie. He also mentions that Seth got into a fight because another person in the line was dressed as Princess Leia.
Star Wars in the massively popular franchise created by George Lucas. It spans movies, television, video games and books. At the time of this episode, the new movie was Revenge of the Sith.
Princess Leia is one of the main characters in the series, played by Carrie Fisher.