Set your TiVos now: Bill O'Reilly and Stephen Colbert will appear on each other's shows on Jan. 18. I'm still recovering from what happened when Colbert took on the Decemberists in a guitar battle, and this duel has the potential to be even more classic. Colbert calls O'Reilly "papa bear" and has based his whole TV persona on him. O'Reilly's got to know he's being made fun of, and I'm curious to see what he'll throw back at Colbert. It might even be enough to make me sit through a whole episode of "The O'Reilly Factor" — and that's saying something.