In preparation for Christmas and the premiere of this year's remaining Doctor Who specials, the BBC's official Doctor Who website launched their online advent calendar for 2009 earlier this month. The advent calendar will feature many exclusive treats over the next five days and door number twenty on the calendar is now available to open due to the fact that today is the twentieth of December. Behind today's door, there's a collection of Doctor Who themed jokes which have been written in a similar style to jokes from Christmas crackers. You can view this Doctor Who related humour here whereas content from behind the calendar's previous doors can be found here. This year's twenty first door on the calendar will be available to open sometime tomorrow and details regarding the next special advent treat will be posted on this site soon. What do you think of these jokes?