As an insurance adjuster, who pays to whom in the following sad story.
Bunch of teenagers have a giant cable spool. The wooden kind. They figure out how to open the center to allow two to climb in. Their friends then push the spool down a long hill. Near the bottom the bouncing throws the two out of the center spindle violently and the spool heads off down the valley floor out of sight. Bystanders and friends alike all rush to the aid of the unconscious duo. As they gather around with their backs to the valley floor, no one sees the spool at full tilt rolling back onto them all clustered together. By definition a valley has two walls.
Only in Russia or a Loony Toons cartoon do you see things like this. But, if it were in the USA, how would insurers handle it?