Jon Stewart and Bill O'Reilly don't seem to like each other much, but they love using each other when it comes to pimping a pet project.

Stewart is making the rounds promoting his movie Rosewater and it includes a stop by O'Reilly's show.

Last month, O'Reilly was on the Daily Show to promote his book, Killing Patton. 

No matter what, when these two square off, it's always interesting television.