On top of the parking garage in between the Sedgwick and Armitage brown line stops, there are occasionally 2-3 people dressed up in costumes and acting out some miniature scene as the train passes. I've seen a 'painter' drawing someone dressed in a toga, shadow puppets behind a screen, and all sorts of other silly little scenes. Everyone gets so excited when they see them! My question is: who are these people? Why do they do it?