BBC Doctor Who site has a 15-question quiz about Christmas Specials present and past:
It’s time to dust off your memories of the Doctor’s festive adventures and find out how much you know about this year’s Christmas Special! You can play the game by yourself or challenge your friends to see who can score the most points!
We scored fairly well but we have to, otherwise we get a visit from a platoon of Judoon who take our Tumblr logins away from us. And then they send us to the Moon.
Go play here.