While doing canoeing, I witnessed a scout stand up in his canoe, raise his paddle over his head, and shout to the scouts on shore,
"HEY GUYS, THROW ROCKS AT ME!!"
Before we could stop the 10 scouts on shore, they had all picked up rocks and sure enough, one of the rocks hit the kid in the head. We brought him to shore, made sure he was okay, then yelled at all the scouts.
I'm sure helmets will soon be required when canoeing...