If I had to guess, it would be a long riff on McCain’s cartoonish refusal to look Obama in the eye. Also bracelets.
Update: John Cole agrees.
It is going to be John McCain going to great lengths to avoid looking Obama in the eye. I can see them having Darrell Hammond holding up his hand to shield his eyes, I can see them having him hide behind the podium, I can see them having the moderator force them to move their podiums so they face each other and McCain then looking down.
That is my bet.