I've read about a variation of this and do it faithfully! Except you have to be driving under an overpass with train tracks, and there has to be a (preferably moving) train on the tracks above you. The idea is that when you press your hand to the car's ceiling, you get to send a wish to hitch a ride on the train going by above you. The moving train takes your wish along with it, giving it quicker travels, more exposure to the world, and thus more opportunities to be fulfilled.