DOCTOR: Your eyes, man. You suffer from headaches?

PERKINS: No, I don't.

(The Doctor bangs Perkins' head on the desk.)

DOCTOR: No headaches?

PERKINS: Well, er. Ow!

(Another thump.)

DOCTOR: Oh dear. You call me a liar?

PERKINS: Well, no, no, no, no. Me head does ache.