The Doctor and Young Kazran in “A Christmas Carol”

Right, so what are we gonna do? Eat crisps and talk about girls? I've never done that, but I bet it's easy. Girls, yeah? [gestures excitedly]

Are you really a babysitter?

I think you'll find that I'm universally recognized as a mature and responsible adult. [shows him the psychic paper]

...It's just a lot of wavy lines.

[looks at the paper] ...Yeah, it shorted out. Finally, a lie too big. Okay, no, not really a babysitter, but this Christmas Eve, you don't want a real one. You want me.

Why? What's so special about you?

Have you ever seen Mary Poppins?

No.

Good, because that comparison would have been rubbish.