I also love the scene from The Unicorn and the Wasp when the Doctor is poisoned.
DOCTOR: Salt. I was miming salt. It’s salt. I need something salty.
DONNA: What about this?
DOCTOR: What is it?
DONNA: Salt.
DOCTOR: No, too salty.
DONNA: Oh, that’s too salty.
Oh and Jackie Tyler cracks me up all the time:
JACKIE: What do you need?
DOCTOR: I need-
JACKIE: Say it. Tell me, tell me, tell me.
DOCTOR: I need-
JACKIE: Painkillers?
DOCTOR: I need-
JACKIE: Do you need aspirin?
DOCTOR: I need-
JACKIE: Codeine? Paracetamol? Oh, I don’t know, Pepto-Bismol?
DOCTOR: I need-
JACKIE: Liquid paraffin. Vitamin C? Vitamin D? Vitamin E?
DOCTOR: I need-
JACKIE: Is it food? Something simple. Bowl of soup. A nice bowl of soup? Soup and a sandwich? Soup and a little ham sandwich?
DOCTOR: I need you to shut up!