Except it's more like, "He was being the wild, free-from-school 11-year-old boy that he is and got the hammock knocked into his eyebrow by his friend and subsequently bumped his head."
As proved by the giant, cartoon-like goose egg on his forehead.
Of course, he's an 11-year-old boy, so he bounced back pretty quickly. The doctor told him he had to lie down for the rest of the day, which of course is the worst thing a kid like him could possibly hear- especially since it didn't come with the benefit of getting to miss school.
I guess whatever game he and his friend were playing was worth that bump. No doubt he'll go back to playing it again tomorrow.
*I've just been informed that the game is called, "Egg Sack." It should be called, "Egg Sock" given that after you're socked in the head, you get a giant goose egg there.