STEWART: You are giving us a great deal of trouble.

DOCTOR: I'm delighted to hear that.

DOCTOR: You, Sir, are a NITWIT!

DOCTOR: But I don't exist in your world!

LETHBRIDGE-STEWART: Then you won't feel the bullets when we shoot you.

DOCTOR: Yes, well I'll tell you something that should be of vital interest to you, Professor.

GOLD: Well, what?

DOCTOR: That you, sir, are a nitwit!

DOCTOR: If you break through the Earth's crust now, you'll release forces you never dreamed could exist!