"Grown-Up!" is an episode of Oobi.
Oobi, Uma and Kako imagine what it would be like to be grown-ups. They dress up and pretend to be grown-ups and do all kinds of grown-up things. In the end, they decide it's much more fun being kids.
Oobi and Grampu are sitting in lawn chairs in the front yard. A pair of firefighters ride by in their fire engine. Oobi imitates the sound of the truck and invites the viewers to join him. Next, a musician walks across the street with his guitar. "Doobi, doobi, doobi-doo," he sings. Oobi repeats this phrase as a businessperson appears, talking on her cell phone. "Grown-ups? Cool!" Oobi remarks. Grampu tells him that children are interesting as well, but Oobi still feels that adults are much more impressive. This gives Oobi the idea to dress up like a grown-up. He and Grampu walk inside and bring out a trunk of old clothes. Kako knocks on the door and decides to play along after being let in.
The boys put on a pair of firefighters' outfits and spot a toy elephant on top of Grampu's piano. They pretend to save it, like real firefighters would. Kako holds the elephant up and pretends that it is talking. "My hero," it says to Oobi. Oobi laughs as Uma walks onscreen. She asks them what they are doing. They explain that adults' professions are "cool." Uma disagrees, stating that kids are "cooler." She asks if she can play as well.
The children find more costumes in the old trunk and pretend to be musicians. Oobi acts as a tambourinist, Kako acts as a guitarist, and Uma acts as a singer. Uma invites the viewers to sing with her. They play music together, but Uma is still convinced that kids are more fun. Oobi, Uma, and Kako search for more costumes as the interview segments begin. They involve Grampu asking preschoolers what they want to do when they grow up.
The next scene shows Oobi, Uma, and Kako dressed as businesspeople. They take out a stack of notepaper and begin shuffling it randomly. Uma talks excitedly on a cell phone as Oobi and Kako get carried away trying to organize their notes. Oobi tries to talk on the phone as well, but things soon become chaotic with paper flying everywhere. Oobi and Kako fall down and realize that adults are not as cool as they had thought. Uma leaves, having proved her point.
Oobi decides to join Grampu in the front yard again. There, he and Grampu see an astronaut preparing for takeoff. They wave to him, but Oobi is not interested. He explains to Grampu that kids are much cooler. Grampu is surprised at first, but he agrees. Oobi waves "goodbye" to the viewers as the episode ends.