It was a ritual thing in a Catholic church. We invent new rituals all the time. This one ended with the famous "let he who is without sin cast the first stone" line.

Almost ended badly - there was an individual present with a more than decent arm who qualified. My 3 year old. Baptized and too young to know right from wrong, therefore technicaly without sin by the local rules. And he would have taken the shot, and hit, if I hadn't swiped his rock.