In order to keep Coop from going evil, Master Yo forces Yin to be his girlfriend for the day. Unfortunately, Yin likes it when Coop loses his cool. Will Yang, Lina, and Master Yo be able to save Yin from herself?
Yang makes a promise to Coop that he will get Yin to go out with her if he does him some favors. Coop finds out that Yang did not keep his promise, causing Coop to let his evil side take him over. Master Yo forces Yin to go out with him while Yo goes out to get the Woo-Foo suspenders and bow-tie that is specifically designed to suck the evil out of good creatures. So, entrusting Yin to make sure Coop stays good he goes to retrieve the bow-tie. At the mall, Yin is being laughed at, making Coop angry. Evil Coop goes on a rampage throughout the mall, but the evil also spreads to Yin, Coop goes back to normal after Yin calls Coop "sugarbeak." Meanwhile, Yo tries to get the bow-tie and suspenders by beating a clown in Clown Foo. When Coop turns the city bad he then realizes that Yin won't ever be with him if he causes destruction, he decides turns Yin evil so she will accept it. After going on a mindless rampage the Yoop Couple (Coop + Yin = Yoop) decide to become Night Masters. Yin is told that she is not evil enough to become the Nightmistress and is intent on destroying Yang to gain her entry to become the Night Mistress. During the battle, Lina and Yang (well, actually just Lina, since Yang admitted long ago) admit there feelings for each other. Just when Lina and Yang are about to be wasted, Master Yo shows up and drains the evil out of Yin. Good Yin then convinces Evil Coop to turn back to normal. Yang and Lina starts to develop their relationship.
Woo Foo weapons introduced
- Woo-Foo suspenders and bow-tie
- This episode features Coop and Yin as the main antagonists.
- Before Master Yo turns the bow, it is purple. When Master Yo turns the bow, the bow is red.
- Altrought Master Yo took away Boopy's (acually was Yo's) Bow and Suspenders of Power, he still wearing it.