Double-Oh Schnozmo! is the eighteenth episode of Season 7.
Cosmo's brother, Schnozmo, comes to visit, claiming to be a secret agent. But when he turns out to be nothing but a con man, Wanda makes him take part in a real spy adventure to spare Cosmo's feelings.
Cosmo and Timmy are playing volleyball with Poof (as the ball) in Timmy's room when Wanda rushes over to Cosmo saying he's got a letter. Cosmo is really excited about the letter, but when Wanda reads about its content, she lies to Cosmo saying he's won a thousand million dollars, then poofs him up a pie. Wanda crumples the letter up and throws it away, but Timmy retrieves it and reads aloud its true content: that Cosmo's brother Schnozmo is coming. Timmy asks who Schnozmo is, and Cosmo reveals that Schnozmo is his brother. Timmy says he didn't know Cosmo had a brother asked why he never met him. Cosmo says that Schnozmo is always super busy and says that Schnozmo invented Canada, found a cure for spaghetti and saved the Walla Walla Monkeys from extinction. Wanda whispers to Timmy that Schnozmo is a con artist and that she doesn't trust him, and that she doesn't want to hurt Cosmo's feelings by saying that, but says she hides her feelings rather well, but blocks off the whole room with barbed wire and bars, hoping to keep Schnozmo out. Wanda says that it is time to play a game called "hide under the bed until Schnozmo leaves" but when she poofs everybody under the bed, Schnozmo is already under there with them. Wanda poofs everybody out from under the bed, and this is where Schnozmo is first revealed.
Cosmo is excited upon seeing his big brother, but Wanda doesn't trust him and searches him. Schnozmo says to Wanda that she's beautiful when she doesn't trust him, and she says that she must be really gorgeous. Wanda tells Schnozmo to give her back her earrings because he apparently stole them, then after that Schnozmo meets Poof, who is teething on his arm. Schnozmo asks who he is, only for Cosmo to reply that it is his nephew. Timmy then greets Schnozmo, but numerous times Schnozmo gets his name wrong and calls him "Lorenzo." Cosmo then asks Schozmo why he needed his help, which was mentioned in the letter. Schnozmo then takes everybody down to the kitchen and eats a sandwich, where he claims that he is a spy for the group "F.A.I.R.I.E (Fairy Agency Investigation of Reconnaissance in Espionage)" He then tells Cosmo he needs his wand, but Wanda keeps Schnozmo from getting it and asks Schnozmo why he needs it. Schozmo claims that the evil Dr. Maybe stole his wand and that he needs Cosmo's before Dr. Maybe could destroy Fairy World. Wanda laughs and says that this was Schnozmo's most ridiculous story yet. She yells at Schnozmo that he can't have Cosmo's wand, but then a bunch of ninjas burst in Timmy's room and claim that Schnozmo must pay. Wanda tells Cosmo to give Schnozmo his wand. Cosmo then tosses Schnozmo his wand. Schnozmo defeats the ninjas, and then tells Cosmo that he needs to keep his wand, a jar of pickles, and Timmy's TV. Timmy asks if they could watch Schnozmo in action, but Schnozmo says that it's too dangerous. He asked Cosmo to make a ham and he poofs away, claiming he'll return.
Wanda says she underestimated Schnozmo and says that he is a super spy, but then two ninjas come back into Timmy's room saying Schnozmo must pay. Wanda screams, but then the ninjas reveal that they are from a restaurant and show that Schnozmo must pay for his meal because he ran off without paying again. Wanda then gets furious and knows that Schnozmo has always been a con artist and was tricking them, and also reveals that her earrings were stolen again. She then takes Cosmo, Timmy and Poof to a tropical island which is where she tracked Schnozmo to. Cosmo thinks that this was all because of Schnozmo's secret plan, but then they hear Schnozmo say "Stay back, Dr. Maybe!" They find Schnozmo, but Schnozmo reveals that he was just a clever fairy using his brother's wand to go on the best vacation ever, then gives a weak cackle. Cosmo now knows that his brother was lying to him and runs off crying, his heart broken. Wanda then angrily goes over to Schnzomo, and he is shocked that they find them and asks how they found him. Wanda says that her earrings have a tracking device in them, and then Schnozmo tries to lie again saying that the evil Dr. Maybe lies in wait, but Timmy says that Schnozmo is the one lying around. Timmy says that Schnozmo's broken Cosmo's heart, and Schnozmo says that he would never break his brother's heart, but Wanda says that he did and that he has to fix it. She poofs up a script and tells Schnozmo to learn the lines and pretend to be the spy that Cosmo thinks he is. Schnozmo rejects doing it, but then Wanda zaps him with her wand and he agrees to go along with the plan. Schnzomo finds Cosmo and tells him that Dr. Maybe was real and that he was lying just to fool Dr. Maybe. Cosmo regains his happiness and tells Schnozmo that he knew he was lying when he said he was lying.
Schnozmo then takes Cosmo to a volcano, where inside Timmy is pretending to be Dr. Maybe, Poof is Timmy's cat and Wanda plays Timmy's assistant, Curlfinger. Schnozmo says that he has come for his wand and that he will dive into a pit of alligators to look for it. Schnozmo doesn't want to dive into a pit full of angry alligators, but Wanda presses a button and Schnozmo gets dumped into the pit. Schnozmo gets torn to pieces, but the wand isn't down there. He then has to go into a buzz saw garden, but doesn't want to again, but then Wanda presses another button and a boot comes out and kicks Schnozmo into the garden, but it isn't down there either. Cosmo then keeps saying that his brother is so brave for facing the alligators and buzz saws. After that, Timmy points to a large door that says "NO WAND" and says that the wand is definitely not behind that door and then points to a button and says to not press the button. Schnzomo then says that only an idiot would press that button, but Cosmo runs forward and presses the button and a giant robotic octopus flies out. It grabs Schnozmo and beats him, but then when it tosses him it grabs Poof and starts to run out of the volcano. Wanda tries to get Timmy to stop it, but the controls to it are jammed. Wanda then tries to stop it with their wands, but the octobot takes the wands and snatches them. Cosmo then spots his brother running away and says that Schnozmo will return because he isn't a liar and is a brave spy.
Schnozmo feels bad for Cosmo, and then sets off to save them. He jumps onto the robot and gives his cackle, and when the octobot tries to smash him, Schnozmo jumps out of the way and ends up smashing itself. After doing it twice, Schnozmo blasted off the robot and onto a large globe. When the robot starts zapping him with rays, but Schnozmo runs around on the globe and projects the lasers back at the robot and it destroys itself. Schnozmo then grabs Cosmo and Poof when they are falling to the ground, but lets Timmy and Wanda fall. Timmy then says that Dr. Maybe surrenders. Cosmo is so happy that Schnozmo saved the day and says he can't wait to tell Wanda and Timmy, but Wanda AKA Curlfinger, says she thinks they already know. Cosmo then asks Timmy AKA Dr. Maybe to give Schnozmo back his wand, but then Jorgen Von Strangle comes in dressed as a ninja and says that Dr. Maybe can't, but he can. He tells Schnozmo that he took his wand away because he repeatedly dined and dashed at the Hungry Ninja Restaurant, in which Jorgen is part owner. Jorgen says that because of his bravery today, he gives him his wand back. Jorgen then tells Schnozmo that he has to eat somewhere else from now on, though. Timmy and Wanda reveal themselves, and Cosmo is really confused. Wanda then says that they should take Schnozmo out to eat so he can tell them all about being a super spy. Schnozmo says that he knows a great restaurant to go to, but after he poofs away with Cosmo, Wanda, Timmy and Poof, Jorgen realizes that his wallet is gone, and his earrings courtesy of Schnozmo. The episode ends with Schnozmo doing his trademark laugh.