My 5 year old attends a forest school on Friday afternoons at a local park, and as it is a nice day I thought I would sit at the other end of the park with a blanket. Obviously there are loads of kids around as school has just finished and it's sunny. Clearly not an issue- I pitched my blanket right in the corner out of everyone's way. Then a large gaggle of children, I would say aged between 7 and 10, came running over and started chucking model planes about (the foam sort), including directly over my head where several of them landed on me. Their parents were sitting about 10 feet away and could clearly see what was happening. I asked the children extremely kindly and politely if they would mind not throwing the planes over my head. Ignored. So I got up and moved to another spot, whereupon the whole group of parents gave me filthy looks and shook their heads at me.
Surely IANBU to expect that, if your child is throwing things over a stranger's head, that you would ask them to stop?!?!! I know kids can be totally oblivious to that sort of thing but if that had been one of my DC I'd have been mortified and immediately told them to stop!!!