"A Case of the Evils" is the 21st (second part) episode of Yin Yang Yo!
After Master Yo accidentally drinks a soda tainted with Carl's cockroach backwash, he starts to act evil. How will the twins Yin and Yang save Master Yo before he uses his Woo Foo to destroy the whole world
- This episode features Master Yo as the main antagonist.
- The way Yin and Yang thought to defeat Master Yo was to use all the weapons from the armory; as a result, all of them got destroyed.