Quotes from "Flatline" (Part 1)

The Doctor: Okay. Uh, same time you left, same place... ish.
Clara: "Ish"? Don't give me an "ish."
The Doctor: These readings are very, uh... ish-y

The Doctor: Impressive.
Clara: No, not impressive. Annoying.
The Doctor: No, this is impressive. (points at Clara) This is annoying. The TARDIS never does this. This is huge! Well, not literally huge. Slightly smaller than usual. Which is huge.
Clara: Yes, I get it, you're excited. When can I go home?

The Doctor: Could you not just let me enjoy this moment of not knowing something? It happens so rarely. 

Clara: I'm, umm... I'm the Doctor.
The Doctor: Don't you dare.
Clara: Doctor Oswald. But you can call me Clara.
Rigsy: I'm Rigsy. So, uh, what are you a doctor of?
The Doctor: Of lies.
Clara: Well, I'm usually quite vague about that. I think I just picked the title because it makes me sound important.
The Doctor: Why, Doctor Oswald, you are hilarious.

Clara: Oh, sorry, I'm talking to someone else who's listening in. Doctor, Rigsy. Rigsy, Doctor.
The Doctor: Hello, barely sentient local.

The Doctor: This explains everything. Their from a universe with only two dimensions. And yes, that is a thing! It's long been theorized, of course, but no one could go there and prove its existence without a heck of a diet.