Feeling guilty about not showing up at Tootie's birthday party, Timmy loans her his godparents for the rest of her birthday, but must subsequently stall her before Mr. Crocker can convince her to reveal the fairies' existence.
Timmy, Chester, and A.J. are enjoying themselves at Mike E. Mozzerella's Pizza Fun House, a party restaurant for kids. Chester enjoys the all-you-can-eat pizza, A.J. thinks the crude robots in the place make feel smart, and Timmy loves the ball pit. However, Tootie is nearby sitting at an empty table, crying because nobody came to her party except for her older sister Vicky, who is scaring off anyone who does decide to show up. Timmy said he would've gone to the party if she invited him but Cosmo and Wanda reminded Timmy that she did and sent him three invitations, which Timmy used to bring Chester and A.J. and skip Tootie's birthday party. Chester and A.J. run off to the arcade to play while laughing at Tootie, but Timmy sulks into the ball pit when he is overcome with guilt.
Back at home, Wanda describes the magical emotion of guilt by performing it on Cosmo, who admits he only missed one of his thousands of anniversaries of Wanda because he pretended to be in a coma. Wanda says that Timmy should do something special to Tootie to make it up to her, but Timmy asks if he can send Cosmo and Wanda to cheer her up instead. Wanda says that only children who are twice as miserable as Timmy can be loaned fairies. They use their wands to look into Vicky's house. We then see Vicky in the process of giving Tootie a swirly. Timmy believes that is enough proof for him and goes with the wish. She runs away and cries while her mother and father comment to her they missed her birthday party because they were afraid of Vicky as well, but when she reaches her room, Cosmo and Wanda are there waiting for her.
Cosmo and Wanda introduce themselves much like how they did when they first met Timmy, the difference being that part of the magic letter "Fairy Godparents" display they created falls on Cosmo. Right as Cosmo and Wanda finish introducing themselves, Tootie immediately begins to wish for things: a pony, a diamond saddle, and then a huge birthday party with a fairy princess theme where everyone in Dimmsdale would show up to her party to bring her gifts. The scene switches to Chet Ubetcha reporting live from Downtown Dimmsdale at Princess Tootie's birthday party. A parade is being held for Tootie, who rides on Wanda and Cosmo who are disguised as a horse and carriage. Behind them, Timmy is stuck sweeping up the "after pellets" from the parade animals, but as long as Tootie is happy he can ignore her without feeling any guilt. That is, until Mr. Crocker shows up to the party and tries tasting the birthday cake. He realizes the cake was made from real butter cream icing, which is not made from scratch anymore, and therefore must be magic.
Mr. Crocker correctly guesses Timmy's plan to loan his fairies to Tootie, right down to the cause of these events. To make matters more difficult for Timmy, Tootie is so overjoyed with what Cosmo and Wanda are doing for her that she wants to tell everyone, since she was never explained Da Rules or the consequences of revealing the fairies. Timmy steps in right before Tootie can reveal his godparents' existence, Tootie squeals Timmy's name happily and hugs him when she sees he showed up to her party, and remains distracted from revealing her temporary fairies when Timmy holds her hand and takes her to open her presents. Mr. Crocker tries to get Tootie to reveal Cosmo and Wanda, but not before giving a gag gift to Tootie, a detention notice which makes a fart noise, which Tootie likes. She is nearly about to reveal her fairies to Crocker, but Timmy manages to interrupt this by pushing over Tootie's pile of presents, causing them all to land on Crocker. Timmy then takes Tootie to the top of her gigantic birthday cake (it's so big they need a lift to get to the top). Mr. Crocker was waiting at the top in a ballerina dress, causing Tootie to freak out and angrily call him weird, although Crocker denies this even though it is what many highly trained professionals have told him.
Once again, Crocker tries to goad Tootie into revealing Timmy's fairies, but they are both silenced when Timmy shoves cake in their mouth. Timmy and Tootie try to leave, but Timmy accidentally leads them right over the edge of the cake. They fall briefly until Tootie grabs hold and clings to the side, while Timmy holds onto her legs. Mr. Crocker tries lowering a microphone so that Tootie can grab on and then tell her secret to the crowd, but as Tootie reaches she slips, and she and Timmy begin to take a long fall toward the ground. While in the air, Timmy clues Tootie into wishing up a trampoline at the bottom, to which she does. Cosmo and Wanda appear as a trampoline below them, and they safely bounce back to the top of the cake, much to Cosmo's enjoyment. However, while landing on the top, they both become stuck in the frosting.
Mr. Crocker attempts to get rid of Timmy for the moment by giving him a lot of balloons, causing him to float into the sky. Tootie grabs the microphone and begins to tell the crowd the existence fairies, when Timmy lets go of the balloons and then falls near Tootie and Crocker, interrupting Tootie and saying that she now has a boyfriend: Timmy. He then grabs Tootie and kisses her while Crocker screams in defeat, his plan foiled. The clock strikes 9'o clock, Tootie's bed time, and she loses her memory of Cosmo and Wanda. Timmy wishes that Tootie would forget that she had fairies and that Timmy called himself her boyfriend. Although she does not remember how she got her party, Tootie still remembers that Timmy was her boyfriend because magic cannot affect true love. Timmy denies this to her, causing Tootie to cry, and Timmy feels guilty again. Cosmo tells Timmy to fake going into a coma, like how he once did when he missed his anniversary with Wanda, as the episode abruptly ends.