Walford

The Tenth Doctor believed the phrase, "This is going to be the best Christmas Walford has ever had" was among the unluckiest sentences that one could utter. (TV: The Impossible Planet)

Behind the scenes
Walford is the fictional east London borough in which the soap EastEnders is set.

The Tenth Doctor's belief that it was unlucky to claim Walford would have a great Christmas is a reference to the soaps infamous tradition of have depressing Christmas specials, in which especially dramatic events, ranging from major revelations to death, would occur.