Clara Oswald: Merry Christmas, Doctor.

Twelfth Doctor: Clara!

Clara Oswald: Hello, you stupid old man.

Twelfth Doctor: You’re back! You’re in my head. All my memories… are back.

Clara Oswald: And don’t go forgetting me again, because… quite frankly, that was offensive.

Bill Potts: Memories – important, right?

From Doctor Who – Season 11 Episode 0: ‘Twice Upon a Time’ (11×00 / Christmas special 2017)