When Cosmo gets picked to host the ultra secret Fairy Convention, he picks the most logical place he can think of -- Timmy's bathroom. Unfortunately, he picked it on the same day that Timmy's fairy hunting teacher, Mr. Crocker, is coming over for dinner!
This synopsis needs improvement.
In the present, Timmy has amazingly aced one of Mr. Crocker's tests (the rest of the kids think it is a sign of the apocalypse), just because of doodling. Timmy then thanks his short attention span. Crocker thinks that Timmy getting an A+ is the result of Timmy's fairies. At the same time, Jorgen snatches away Cosmo and Wanda. Crocker then approaches Timmy, asking if he could come over to his house for dinner, implying that he will take the opportunity to search for his fairies.
In Fairy World, Binky has finally stopped spinning and is pointed at Cosmo's name. And Cosmo knows just the place to have the next convention.
At Timmy's house, his family is getting prepared for Crocker. Timmy is instructed to install the "good" toilet seat in the upstairs bathroom. However, he finds the entire bathroom transformed into the fairy convention. He finds Cosmo and Wanda, warning them that if Crocker catches a whiff of fairies, he'll barge right in. Luckily, Crocker is told by Timmy's mom that he has to knock on the door first, which Crocker does. Hearing the knock, the fairies restore the bathroom to normal and hide along the walls. As soon as Crocker is dissatisfied, the convention goes on. Furthermore, Timmy is informed that fairy conventions are very short. However, he asks out loud if Cosmo didn't invite someone who could spoil everything. As it so happens, Cosmo had hired Britney Britney, who knocks on Timmy's house door. Crocker quickly gets suspicious and voices them out loud.
When Britney goes to the bathroom to powder her face, the fairies restore the bathroom again and go unnoticed. When she shows a Shirt button for the Cosmo Con, Crocker finally gets suspicious enough that he decides to storm the bathroom without knocking. However, he is blinded by various things pelted at him, before being thrown out of the house. Because Jorgen perceived that Crocker nearly discovering them was an act, he declares the convention over.
Crocker tries storming the bathroom again, only to come in on Mrs. Turner. She screams in terror, but it turns out she was just clipping coupons off a newspaper instead of sitting on the toilet. Mr. Turner then boots him out of the house.
When everyone gets back to eating dinner, Mr. Turner tells Britney to "hit it". She does so and begins dancing with her backup dancers supporting the dancing. Mrs. Turner shocked states her husband doesn't tell her to "hit it". She then angrily walks over while pulling up her fist. It then shows Mrs. Turner booting Britney out of the house. She angrily tells herself she will do no more private gigs.
As Timmy begins to relax, he once again finds that his bathroom is now hosting a boating show by Wanda. The episode ends with a foghorn with Timmy's parents thinking it was an actual fart from Timmy. Mr. Turner tells his son to keep his door closed if he wants to do that and lastly says "Not mine!".