This television episode refers to:
Michael and Pam are at the Job Fair at a local high school. Michael notics that Pam does not have Dunder Mifflin paper, and tells her to go back to the office to get ultra white card stock. Pam's reply is "Are you serious?" to which Michael answers "Yes. And don't call me Shirley.", botching the famous line from the movie 'Airplane!'.