Hot on the heels of Coke Zero's Ugly Sweater Generator comes another Christmas sweater-themed campaign -- but this time, it's for charity. Save The Children (UK) is running a social media campaign centered around Christmas knits to raise awareness of its work. Comedian Dom Joly stars in two videos on its YouTube channel alternatively as Bjorn, who loves classic Nordic knits, and Brian, who prefers "wacky" sweaters (or jumpers as they are known in Britain). Viewers will be encouraged to get on Twitter, upload a picture of their own Christmas jumper and tweet with #xmasjumperday and the hashtag either #Nordic or #Wacky. The winning team will be decided on December 13, the charity's official Xmas Jumper Day on which people are being encouraged to donate at least one pound. Save The Children will also launch a Facebook app , which is set to will analyse people's Facebook timelines to tell them which sweater style they are best suited to. All the activity was created in-house.