Coat hooks in my church’s education wing are at a small child’s shoulder height, so that the small children can easily hang their coats. A child could fall “down” and catch his collar on one of these hooks, although it seems very improbable.
I think it is safe to assume that bigger kids were mimicking the "Malcom in the Middle" trick or similar antic from a movie. They just didn't have any duct tape on hand.
Then they can just as easily put their feet back on the ground and stand up again and get off the hook.
I’d bank on a prank gone wrong in this case.