In the movie Opposite Day, a group of children are fed up with the rules and limitations placed upon them by the adults in their lives. They stumble upon a magical device that can make their wishes come true and decide to declare an Opposite Day, where the world will turn upside down.
As a result, the children wake up to find themselves in adult bodies, with jobs and responsibilities, while their parents and other adults in the community have been transformed into children. Chaos ensues as the children struggle to navigate their new adult lives and the adults try to adjust to being children again.
Throughout the film, the children come to understand the challenges and stresses that come with being an adult, while the adults rediscover the joy and wonder of childhood. As they work to reverse the effects of the Opposite Day, both groups learn valuable lessons about empathy, understanding, and the importance of maintaining a childlike sense of wonder in the face of adversity.