When a young boy makes the transition into manhood, he is blessed with certain physical attributes.  In Cartman's case, he gets pubes.  After the other boys tell him that pubes don't count unless you grow your own, Cartman realizes he's been tricked.  When Scott Tenorman won't give him his money back, Cartman goes medieval on him.  Radiohead guest stars and plays a role in Cartman's elaborate plan for revenge.