We went on a walk the other day with some other parents and their children. Their 3.6 yr old threw a stone at DD's chest. It didn't hurt her. She didn't cry, was just very surprised.
The mother asked for an apology and as it was not forthcoming said the culprit couldn't have any of the communal snack which I had brought, had in my bag and we were planning to eat at an appointed place on the walk, about 5 minutes on. The child was stubborn and ended up having a tantrum about it.
I felt it was totally out of proportion as a reaction but I was the one with the snack in my bag.