If you want to see bravery, watch Colbert at the White House Correspondence dinner in 2006. Part 1, Part 2, and Part 3. Incredible. During the Helen Thomas skit there is a separate video that captures Bush's reaction. I don't think he's happy. Apparently Colbert was booked by the outgoing president of the White House Press Corps Association. He'd probably have been fired if he weren't already leaving after this. A Wiki overview here.