b997eee8_CCG___What_s_That_Inside_Joke___In_joke
[Card] The Doctor (10) - The Man in the Brown Suit [Exp.] S10 [Type] Ref [In-joke] 
The subtitle is taken from a book by Agatha Christie, with whom the Doctor co-stars.
Unauthorized Dr. Who CCG - What's That Inside Joke?
In-joke