Just like Madonna on Letterman?

Question

I remember the night Madonna and Letterman got into a verbal sparring match.
http://en.wikipedia.org/wiki/Madonna_on_Letterman

Can you think of any contentious moments you've seen on TV (or heard on the radio).

Answer 1

Rosie O'Donnell and Tom Selleck went a few rounds about gun control, when he was on her show to prevent a movie.

http://www.nrawinningteam.com/norosie.html

Answer 2

Bill O'Reilly was a blast on Letterman.
I particularly loved the part where he referred to British Intelligence as "M (one)-6" instead of "MI-6".