SpongeBob visits his Grandmother's house, where he indulges in the joys of childhood: eating homemade cookies, licking batter off the spoon and being told stories. As soon as the clock strikes 3:00 PM, SpongeBob has to go back to work and is given a ride there by his Grandma. When they arrive, she kisses him goodbye, leaving a kissy mark that is visible on his forehead.
SpongeBob is then teased by everyone at the Krusty Krab and runs home crying. At home, Patrick consoles SpongeBob about this, recommending that SpongeBob show his Grandma that he is not a baby anymore by acting like an adult. SpongeBob and Patrick go to Grandma's house wearing false sideburns, and when she answers the door and tries to kiss him, he cuts her off, explaining to her that he is an adult now.
Grandma offers them cookies which, while SpongeBob refuses, Patrick gladly gobbles down. When SpongeBob confronts him on this about-face, Patrick exclaims, "Being a grown-up is boring," and that he enjoys being treated like a baby. SpongeBob attempts to eat a cookie himself, but Grandma stops him, giving him nutritious steamed coral instead. She moves on to story time, telling Patrick a whimsical tale while giving SpongeBob a thick technical manual to read by himself. She then gives Patrick a sweater "with love in every stitch," while SpongeBob receives unwrapped office supplies. Soon, the clock strikes 3:00 PM and she reminds SpongeBob to go to work while she sets Patrick down for a nap.
SpongeBob starts walking toward the door, commenting on how his busy adult life will make it hard to visit very often. As his Grandma seems unconcerned with this, SpongeBob eventually leaves. However, he bursts back inside, his manly sideburns falling away. He sobs that he doesn't want to grow up, that wants to be treated as a baby again and live like one: eating cookies, drinking from bottles, wearing diapers and homemade sweaters, riding in a red wagon, cuddling with a teddy bear named Mr. Stuffykins, rocking on a wooden seahorse, and getting kisses on his boo-boos. He then cries so intensely that he floods the house.
Grandma calms him down and pulls a plug in the floor to drain his flood of tears. She tells SpongeBob that he doesn't have to be a baby to get her love and that he will always be her baby no matter how grown up he gets. She presents him with a cookie in one hand and his fallen sideburns in the other. SpongeBob gladly accepts them both, but asks her to not bring it up at the Krusty Krab, to which she warmly replies, "No problem." As SpongeBob and his Grandma embrace, however, Squidward and the Krusty Krab customers peer in through the window, laughing wildly as the episode ends.
SpongeBob and Patrick in a deleted scene from storyboard
In the final scene, the kitchen changes locations.
When SpongeBob says "I don't?" his reflection looks like his mouth doesn't move and was open as if he were still crying.
When Patrick uses his mouth as a vacuum cleaner to eat his cookies, one can clearly see that he's eaten all of them, but one rolls out.
When Squidward and all of the Krusty Krab customers are seen laughing at SpongeBob hugging his grandma at the end, Harold "Bill" Reginald was green instead of blue.
A fish was talking to SpongeBob and at one point, his arm wasn't on his body.
A glass of milk and a plate of two cookies are shown on the table when Patrick says, "Besides, I don't get jazz," but in the next shot when SpongeBob starts blowing bubbles out of his pipe, they are both gone.
In the first shot Clayton is blue, in second shot he is purple, and in following shot, he is blue again.
After SpongeBob says, "What am I waiting for?" before he runs to his grandma's house, SpongeBob's tie and collar fold are missing from his shirt.
When SpongeBob says, "Tell me another story about when I was a baby," his eyelashes are missing.