"Babysitter!" is an episode of Oobi from the second season.
Oobi is reading a board book in the living room while Uma plays with multicolored blocks. Uma tells Oobi that she is building a house for her doll. Grampu greets the children and helps Uma build her block house. Uma notices that he is wearing a purple bow tie. Grampu explains that he is wearing it for his night out with Inka, during which he plans to dance the polka. Grampu demonstrates his dance and Uma asks if she can dance with him and Inka. He makes it clear that only adults will be dancing, and that he has hired a babysitter to take care of the children. This upsets Uma.
Grampu hears the doorbell ring and answers the door. A teenaged puppet named Randy walks inside and greets the family. He gives Oobi a "high-five" and attempts to exchange one with Uma as well. She declines his offer as Inka calls Grampu from outside. He rushes to her after saying "goodbye" to the children. Oobi invites Randy to read his board book from earlier. Randy gives Oobi the nickname "Oobi-Dude" and tries to make Uma feel better. He offers to help Uma with her block house, but Uma declines. Randy decides to play a guessing game with Oobi, in which he acts like Grampu.
Uma cannot help but laugh at Randy's impression. Randy pretends to have a conversation with Uma's doll and dances the polka with it, eventually winning Uma over. She gives him the nickname "Randy-Candy" and plays another guessing game with Oobi. Randy tells the children that it is time for bed. While Oobi and Uma get ready, an interview segment plays. It involves Kako asking preschoolers about their babysitters. The next scene shows Randy singing the "Rockabye Lullaby" song to Oobi and Uma. Grampu returns as he sings. Oobi says "goodbye" to Randy and to the viewers as the episode ends.