Boos made their first appearance in Super Mario Bros. 3, but their most prominent role came in Super Mario World. In the classic video game, Boos would initially be stationary, but as soon as Mario turns his back or faces away, they would pursue him. However, if Mario looks at them, they freeze and don't move. Boos have become a staple in the Super Mario series, and everyone will immediately know you are a fan when you wear this Boo Ghost Super Mario Bros. T-Shirt!
