Yin! Yang! Yo! - Season 2 Episode 20

Yang and Carl fight over a replica of an enchanted hammer that is for sale in a store where Mastermind works. Mastermind tries to ruin their lives by fusing the two back-to-back. The only way to undo the curse is to cooperate. After they try to waste each other, they go to Carl's Castle, where Yang and Herman become close friends, and Carl's mom takes a liking to Yang. Afterward, they go to Yang's house where Carl impresses Yin and Yo with his cooking and grooming skills. The enemies will have to learn to be friends to be free of each other. Yin plans a 'fun' slumber party, but she starts blasting people carelessly and acting obsessive about the party, and confines Yang to his room. Meanwhile, one of the Woo Foo Elders contacts Yang, and he activates the "Woo Foo Book of Ultimate Eeeeeevil" to turn Yin's friends into mind-eating zombies. Yin will have to stop the rampage without sacrificing the fun of her slumber party