b997eee8_CCG___What_s_That_Inside_Joke___In_joke
[Card] Knock, Knock [Exp.] Key [Type] PQ [In-joke] 
A knock knock joke, which is always appropriate for the show’s title. The quote is actually from The Daleks’ Masterplan, but taken out of context.
Unauthorized Dr. Who CCG - What's That Inside Joke?
In-joke