Mary Poppins

 was something the Eleventh Doctor wondered — in the midst of a discussion about his fitness as a babysitter —if the twelve-and-a-half-year-old Kazran Sardick had seen. The Doctor stopped himself before fully comparing himself to Mary Poppins, saying that the analogy would have been "rubbish". (DW: A Christmas Carol)
 * Though the Doctor never specifically called Mary Poppins a film, any common sense reading of the scene would indicate he was talking about the film — largely because of the line, "Have you ever seen Mary Poppins?"