Use of slingshots is very common at Cub Scout day camps. They'll typically set of a shooting range with all sorts of stuff to plink at, and then use dog kibble (can't remember which brands are nice and round) as ammunition. The idea is that they can leave it on the ground outdoors and the environment is unharmed beyond the temporarily fat stomachs of a few happy racoons.

Its a great way to start young folks learning the rules of firearm safety without taking someones head off.

You should see what some unaware 11-13 year olds do with 22's at summer camp. The shooting range directors take the safety aspects veeeeery seriously and I've seen 11-year old boys kicked out of the area for the week in tears.