b997eee8_CCG___What_s_That_Inside_Joke___In_joke
[Card] Samantha Briggs - Brassy Scouser [Exp.] TL [Type] PQ [In-joke] 
The quote is a bit of a joke on the idea that she came on as a possible companion, but then decided not to stay with the show.
Unauthorized Dr. Who CCG - What's That Inside Joke?
In-joke