Jesse and Joey are trying to come up with a contest to have on their radio show, "Rush Hour Renegades", and the subject of TV theme songs is brought up by Joey, with the idea of asking listeners if they know the lyrics to a certain theme song. Nicky and Alex like it when Jesse starts singing the theme song for the show Three's Company, in response to Joey's idea. Michelle has been selling lemonade on an extremely hot day and surprisingly, she has earned $221. Danny has a painting of his great-great grandfather, General Cornwall Tanner, enlarged and completely restored. Michelle, without telling anyone how much she earned, does tell the guys she's going to the candy store when she has Kimmy take her out to spend the money. While Michelle and Kimmy are out, Stephanie tells the guys that Michelle earned more than $200 and of course, Danny is shocked, but not as shocked as he is when Michelle and Kimmy bring home a miniature donkey named Shorty. Michelle explains that she and Kimmy were on their way to the candy store when they happened upon a traveling petting zoo, where she saw Shorty and bought him for the $221 she earned. Problem is, Shorty can't be taken back to the petting zoo, because the petting zoo is now on its way to Seattle. Danny feels that he has no choice but to let Shorty stay the night and Danny lets it be known that Shorty is to sleep in the back yard and that he'll decide what to do with Shorty tomorrow. While everyone is asleep or at least trying to get to sleep, Shorty starts making his braying 'hee haw' sound. Everyone wakes up and a neighbor complains about Shorty. D.J. wants to get some sleep so she can look good when her senior picture is taken tomorrow. By this time, it's almost midnight. It seems that Shorty is quiet whenever Jesse sings the Three's Company theme song, so Jesse sings that song to Shorty all night in order to keep him quiet. In the morning, Stephanie discovers that Shorty has chewed a chunk out of a map she made for geography class. D.J. is having an allergic reaction to Shorty that is causing D.J.'s eyes to look puffy and she's all sniffly. Shorty then eats a hole through the painting of Cornwall Tanner. Everyone likes Becky's idea of donating Shorty to the local children's zoo.