Back at the Barnyard (2007)

Season 1: Episode 9

When Otis gets a hypnosis kit, he accidentally hypnotizes himself so that he tries to destroy the farmer whenever he hears the sound of a bell. Now, the other animals must try to protect the farmer while trying to cure Otis at the same time. But every time Abby tries to stop Otis from hurting the farmer, he thinks she is hurting him.