QI, Series I

[Question:
"How were the rings around Saturn actually formed?" Brian Cox and Alan Davies, sitting on the opposite sides of the studio, both pull out their "Nobody knows" cards]

Brian Cox:
I'm going to, to play the card there.

Stephen Fry:
[looking at Cox] You are right! You're a true scientist. The fact is that nobody does really know, do they.

Alan Davies:
[pointed cough]

Stephen Fry:
[turns to see Alan with his card] Well done!

Alan Davies:
[Formally] Thank you.