RUBY: But hold on. I can't call you Doctor. No, I want to know your name.

DOCTOR: Yeah, that's er... that's tricky, because I was adopted, and the planet that took me in, they were kind of... they were kind of posh. They'd use titles like the Doctor, or the Bishop, or the Rani, or the Conquistador. Say Doctor for a thousand years and it becomes my name.