12/14/2011 11:57 am ET | Updated Dec 15, 2011

Stephen Colbert Fires Back At Anderson Cooper, Ridiculist (VIDEO)

Stephen Colbert and Anderson Cooper have more beef to work out.

Cooper put Colbert on the "Ridiculist" last Wednesday. He admonished the Comedy Central host for mocking William Tapley, a religious conspiracy theorist who claims that Denver International Airport is full of phallic symbols, just this month. Cooper said Tapley was on the Ridiculist in June, and called Colbert "six months tardy to this particular phallic party."

Colbert was only too happy to respond on Tuesday night. He referred to Cooper as a "Casper-American" and said that the "Ridiculist" segment uses the font "Sans Serif whack-a-doodle."

"It was foolish of me to believe that even on my best day, I could beat Anderson Cooper to a phallus party," Colbert said. "I am sorry." He went on to apologize for touching a story that Cooper had already done, and chose to tackle one that Cooper hasn't covered yet: the phallic symbols on Cooper's CNN show. See the segment in the clip above.

Colbert's hit at Cooper is just the latest in the notorious rivalry between the two cable hosts. Cooper has put Colbert on the Ridiculist before, and Colbert once tore into Cooper for his on-air giggle fit over pee puns.