What Is A Baseball Fan What is a baseball fan? The word fan is an abbreviation of fanatic, meaning “insane”. In the case of baseball fans, the term is appropriate. They behave insanely, they are insane about trivia, and they are insanely loyal. Baseball fans wear there official team T shirts and warm-up jackets to the mall, the supermarket, the classroom, and even-if they can get away with it-to work. Baseball fans behave insanely, especially between April and October. In addition, they cover the walls with items of every kind. When they go to a game, which they do as often as possible, the true baseball fans put on their team colors, pin on their