The Iron Buns are a body part that only appears in the episode "Krusty Krushers."
Iron Buns are a pair of metal buttocks that Patrick develops after a large amount of butt exercising in preparation for the main wrestling competition.
Role in episode
Patrick had previously done various butt exercises that made his buttocks strong. It is also shown that Patrick developed them while he was sleeping. As a result, Patrick was able to generate his iron butt within seconds before the twowrestlers could "drill" onto SpongeBob and Patrick on the bed that was in the main stadium.