Pinky Dinky Doo is a girl who lives in Great Big City with her parents, her little brother, Tyler, and their house pet, Mr. Guinea Pig. When a problem arises, Pinky says, "That gives me an idea" and Tyler says, "Pinky, are you going to make up a story?" and Pinky will say, "Yeserooni positooni!", dancing to a cardboard box, her Storytelling Box, with Tyler and Mr. Guinea Pig. Using chalk and her imagination, she tells a story. In season 2, Pinky uses the Story Pad, a notebook in which Pinky draws pictures for her newer made-up stories, whenever the Story Box is not available. During the made-up story, Pinky must "Think Big", at which point her head swells and she comes up with an often wacky solution to the problem while singing "If I have a problem, don't know which way to go, I think and think and think and think, and suddenly I know!". In Big Blob of Talk, instead of thinking big, Pinky listens big instead. In Back to School Is Cool, Pinky's hair swells instead of her entire head due to her having a bad hair day. In Tyler Dinky Doo to the Rescue, Two Wheel Dreams, Go to Bed Tyler!, and Tyler's Big Idea (series finale), Tyler thinks big instead of Pinky. In Shrinky Pinky, Mr. Guinea Pig does the thinking.