It's Joke Day, an especially silly day for the Fraggles. Boober tries to run away from the celebration, but he sees a big, round, pink, scary Glob invade the Great Hall and surreptitiously start eating Doozers. No one else believes that the Glob is dangerous, so Boober has to battle the Glob by himself.
Everyone has to dress up in silly costumes and tell jokes all day on Joke Day. The celebrations include the Traditional Medley of Knock-Knock Jokes.
This is another important episode in the continually evolving relationship between the Fraggles and the Doozers. By this episode, Cotterpin knows Red Fraggle, but this is the first time she meets Boober. A running gag involves Boober not being able to tell Cotterpin apart from any of the other Doozers, although he does learn her name by the end of the episode.
In this episode, the background music for Uncle Matt'spostcards changes. In previous episodes, there was a different instrumental during Matt's narration, but beginning in this episode, Matt gets a background theme called "All Around the World." The song itself is never sung in the American episodes, but it was released as a single in the UK. A portion of said version is heard in the behind-the-scenes special Down in Fraggle Rock.
This episode features the only interaction in the series between Boober and Cotterpin.