The Fresh Prince of Bel-Air: Season 4, Episode 7

4 - 7: Hex and the Single Guy

It's Halloween and Hilary decides to hold a séance with a somewhat well-known psychic in order to say goodbye to Trevor and forces the family to go with her. However, when Will begins to mock the psychic, he puts a curse on him, resulting in everyone else at the mansion having bad luck. Will then goes back to the psychic's house and begs him to lift the curse.