Poof gets The Baby Flu, and the only way to cure it is to make him laugh. So Timmy gets The April Fool to help.
Poof starts to act very weird, so Cosmo, Wanda, and Timmy take him to the fairy doctor. Dr. Rip Studwell says Poof caught "The Baby Flu", which is a very common sickness among fairy babies. He says that the only way to cure it is to make him laugh a lot. At home, Timmy, Cosmo, and Wanda are having a hard time getting Poof to laugh. Timmy suggests they get The April Fool to come, and tell some jokes. Wanda thinks that is a good idea, and poofs him up. Suddenly, a confused April Fool asks Timmy and his fairies what they want. Just before Wanda could say anything, a rabbit, and a red-haired girl poof up, and say they have been looking all over for him. Awkwardly, The April Fool introduces his younger sister, Stiffy, and Nick, The Easter Bunny's son, and a family friend. Timmy then notifies that Stiffy looked so much like a human girl, and that he thought she was one. Stiffy then says that she is half fairy, and half ogre, and has no wings at all, but still flies. Next, Wanda tries to get back on topic, and says that Poof caught The Baby Flu, and needs to laugh in order to get well. The April Fool says that he asked the right person, and starts to do silly stuff. Meanwhile, Timmy, Stiffy, and Nick start talking about something. After a while of sillyness, Poof barely gets a giggle, and The April Fool gives up. Then Stiffy, Nick, and Timmy start doing a few silly acts, which make Poof laugh. When Poof was almost cured, Dr. Rip Studwell poofs up, and says that he discovered a better cure for the baby flu. Timmy asks what that cure is, and Dr. Studwell says that it is a special vaccine. Wanda then says that Poof hates shots, and that he should know that. Dr. Rip Studwell says "too bad", and poofs away. As Wanda says how rude that was, Timmy, Stiffy, and Nick have already cured Poof. Wanda thanks them, and The April Fool gets angry that he wasn't the one that made him laugh. Suddenly, The April Fools watch alarm goes off, and he says that him and Stiffy have to go. Timmy says bye, and tells Stiffy that they should talk more. After they left, Jorgen poofs up, and gets mad at Nick for no reason. Nick says that he likes doing that a lot, and that Jorgen is his #1 fear. Jorgen grabs Nick, and poofs away. Wanda says that she is glad Poof is finally cured. Then suddenly, Poof starts to hiccup. Dr. Rip Studwell poofs up and says that Poof has The Baby Cups. Timmy moans "here we go again", and it is the end.