It's an episode about sports in which multiple characters shout about "GUTS." Do you seriously think a mind of my vintage WOULDN'T immediately go to the Nickelodeon show? I mean, the alternative would be to make a Berserk joke, but that would almost certainly require going in directions I don't feel like going in.
But yeah, I now choose to believe that the Claire Bible is carved onto a piece of The Aggro Crag.