Michael Buffer, the boxing ring announcer best known for his catchphrase, "Let's get ready to rumble!", made a guest appearance as himself in "Damien". Parker and Stone originally planned to use the catchphrase without Buffer, but when they learned that Buffer had legally trademarked the phrase, they included him in the episode since getting the rights for the catchphrase cost nearly as much as hiring Buffer for a guest appearance. Parker and Stone both said Buffer was friendly and they enjoyed working with him. Voice actor Mike Judge, star of "Beavis and Butt-Head" and "King of the Hill", had originally been slated to provide the voice of the Damien character, and even recorded several lines for the part. However, since Judge lives in Austin, Texas, it proved too difficult to for him to come back and rerecord lines as the script and episode changed, so Stone instead provided the character's voice. Judge later provided Kenny's un-muffled line when he removed his parka in "".