Humbug (exclamation)

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Humbug was an exclamation the Ninth Doctor used after Charles Dickens refused to participate in Gwyneth's séance. (TV: The Unquiet Dead)

Behind the scenes

The use of "Humbug" in The Unquiet Dead is a reference to Dickens' own character Ebenezer Scrooge, who is widely known for uttering the exclamation.