Theatre State is when a person or a group of people become like characters in a play. It means to act differently than you normally would and to take on a new persona. For example, when you go to school, you may normally act like yourself and talk in your own voice. But if you're in theatre state, you may pretend to be someone else and talk a different way, like a character from a play or movie. It's like pretending to be someone else for a short time and having fun with it.