Stupid Cupid is the seventeenth episode of Season 7.
After being rejected yet again by Trixie, Timmy Turner seeks help from Cupid, only to find he's left on vacation. So Timmy takes Cupid's bows and arrows and entrusts Cosmo into the temporary role of Cupid so he can make Trixie fall in love with him. Unfortunately, Cosmo messes everything up again by missing his shots and hitting the wrong targets, and soon Cosmo, Wanda, Mr. Turner, Mrs. Turner, and Mr. Crocker are head over heels in love for all sorts of things!
Tonight will be the Romance Dance but Timmy does not have a date. He thinks his friends don't have dates either but he sees that A.J. made three dates for himself, Chester and Elmer. Timmy thinks Sanjay does not have a date but he sees a girl that looks just like him. She is Sanjay's date and Sanjay says that his date's name is Kimmy and she has three goldfish. Wanda says that is even creepier. Timmy decides to ask Trixie to the dance. But when he asks Trixie, she rejects him. She pulls a lever and a big boot kicks him out. Timmy lands in the garbage bin.
At Timmy's house, Wanda finds a love letter from Juandissimo. Timmy wants to find ways to make Trixie fall in love him. Wanda explains that Da Rules say that their magic can't help him with love. Timmy knows someone who can help him and that's Cupid. At Cupid's house, Timmy asks Cupid to shoot Trixie with one of his arrows but Cupid refuses him because he's going on a holiday. Timmy decides to take Cupid's bow and arrows but Wanda says that it is too risky because they are guarded by Cupid's love birds. When Timmy is going to take Cupid's bow and arrows, the love birds appear in front of him. Cosmo throws the jerky to distract the love birds.Timmy takes Cupid's bow and arrows and Cosmo,Wanda and Poof poof Timmy and themselves back at Timmy's house.
At Timmy's house, Cosmo wears Cupid's diaper to be more like Cupid. Wanda tells Timmy it is a bad idea because if the arrow hits the wrong butt, it could ruin someone's life. Cosmo takes one of Cupid's arrows and shoots. The arrow hits Wanda and she falls in love with Juandissimo when she sees the picture on the love letter. When she poofs away, Cosmo says that his life is ruined. But he thinks she will bring more jerky. Timmy says that they know the arrows have worked. At Trixie's house, Timmy tells Cosmo to hit Trixie with an arrow when she opens the door. But instead of shooting her, he hits her on the head. When Timmy asks Trixie to the Romance Dance, she rejects him and pulls the lever and the big boot hits Timmy and he falls in the garbage bin again. Cosmo shoots and the arrow hits Timmy's dad, making him fall in love with a dying rose bush. He also named the rose bush Rosy.
At Juandissimo's house, Wanda arrives and puts on the lipstick (messily) to kiss him. But Juandissimo sees Wanda has jerky in her teeth. He tells her to floss and brush. But Wanda becomes weird. Juandissimo flies away and Wanda chases him. In the library, Timmy tries to tell him to be like a cupid. Cosmo is going to shoot the arrow but he wants to know what Timmy saying. He let go of the arrow and checks the dictionary. The arrow hits Cosmo, making him fall in love with his reflection. In Fairy World, Juandissimo tries to get away from Wanda but she catches him by lassoing him.
Outside the school, Cosmo talks to his reflection. Timmy puts all the pictures of himself all over the place,telling Cosmo that when Trixie looks after a hit by an arrow she'll fall in love with him. The car door hits Timmy. Timmy's mom says that they have to stop Timmy's dad from marrying a rose bush. Mr Crocker comes and gives an A to Timmy. But he tears it and gives him an F. Timmy sees Trixie and tells Cosmo to shoot. When Cosmo shoots, the arrow hits Timmy's mom. Cosmo shoots another arrow. Another arrow hits Mr Crocker. Then both Timmy's mom and Mr Crocker fall in love with each other. Then Poof shoots Trixie with an arrow. When Trixie turns around, she sees a picture of Timmy. She says Timmy's name. She asks did she just say Timmy. Then the bus door closes. As the bus drives away, Timmy asks Trixie to go to the Romance Dance. Trixie says yes. And she also says "I love you, Timmy Turner".
At night at Romance Dance, Timmy's life becomes great with Trixie falling in love with him. But before he could kiss her, Mr. Crocker announces that he is getting married. His fiance is Timmy's mom. And Timmy's dad says that they going to have a double wedding. Trixie wants to kiss Timmy but Timmy says he cannot let his dad marry a rose bush and his mom marry Mr Crocker. He takes Cosmo and Poof with him. Timmy wishes that Cupid is here. Cosmo poofs Cupid, interrupting the cruise ship limbo contest. Timmy tells Cupid what happened while Cupid is on vacation. Cupid becomes shocked. He takes his bow from Poof. Then he looks at Cosmo who is holding a mirror and wearing a diaper. Cupid says that Cosmo can keep the diaper. Cupid tells Timmy he will clean up the mess but it will cost him. He poofs his Anti-love arrows. First,he shoots Timmy's dad. Timmy's dad says "It's over. It's not you, it's me. But it's mostly you". Then he drops the dead rose bush. Next, Cupid shoots Cosmo. Cosmo says "We're through. It's not you, it's me. But it's mostly you". Then he drops the mirror.
At Juandissimo's house, Juandissimo says that he surrenders for Wanda. Then one of Cupid's anti-love arrows hits Wanda. Wanda says "How dare you? I'm a married woman". Then she takes out her handbag and hits Juandissimo and poofs away. Mr. Crocker's mom asks Timmy's mom that she does take Mr Crocker to be her husband. Timmy tells Cupid to fire. Mr. Crocker is going to kiss Timmy's mom but Cupid shoots them with his anti-love arrows. Timmy's mom says "How dare you? I'm a married woman". She takes out her handbag and hits Mr. Crocker and walks away. Then she comes back and hit him again. Cupid says that Timmy causes a lot of trouble. Timmy's punishment is washing and ironing all of Cupid's vacation diapers. Cupid hopes Timmy learns his lesson and poofs away. Trixie comes and hits Timmy with her handbag. At Timmy's house, Timmy is glad that his parents are still together and everything is back to normal. Timmy's dad is telling Timmy that he is taking Timmy's mom to dinner. He shows him the outfit that he made for her. It is made from a rose bush. Timmy's mom thinks there is a squirrel in it. The squirrel comes out. Timmy's dad says that Timmy's mom could get used to it. The squirrel attacks Timmy's dad and the episode ends.