^^
What Rukas said. This is from wikipedia:
spin-off and counterpart of The Daily Show which, like The Daily Show, critiques politics and the media. It satirizes personality-driven political pundit programs, particularly Fox News' The O'Reilly Factor. The show focuses on Stephen Colbert, a fictional anchorman character played by Colbert. The character, described by Colbert as a "well-intentioned, poorly informed, high-status idiot", is a caricature of televised political pundits.
He's purposely playing dumb.