Any time Alan Davies gets the better of anyone, particularly when he wins and in the incident where he switched roles with Stephen Fry and proceeded to bully him like you wouldn't imagine. "I've been waiting for this opportunity!" indeed.
Stephen: [holding forth on how bees navigate using the sun] Amazingly, they can even do this on overcast days and at night by calculating the position of the sun on the other side of the world.
Alan: Has it occurred to you that they may not be using the sun? That whoever worked that out is wrong.. "Even when you can't see it or it's on the other side of the world, they still use it," and the bees are thinking, "No we don't, we just remember where we live!" Why is it so remarkable that they know where they live?
Stephen: Well, because they have only 950,000 neurons as opposed to our ten billion neurons in our brains.
Alan: But they've only got one thing to remember: where they live.