As previously reported, O'Reilly and FOX News criticized Michelle Obama for inviting the rapper to the White House to read poetry because he celebrates violence and cop-killing in his lyrics.
Defending Common, Stewart argued that conservatives needed to be "consistent" with their outrage pointing to the story of Leonard Peltier who was convicted of killing two federal agents back in the '70s.
"Guess who wrote a song about Leonard Peltier? Bono. Guess where he was? The White House. Booh-yah!” Stewart said.
Check out their debate on Common below.