Now that the Mannequin Challenge has run its course, it’s time for ‘the Backpack Challenge.’  That’s where you run between two rows of people who throw their backpacks at you full-force.  Naturally you don’t make it far.  It’s a terrible idea, since backpacks are heavy and you could get hurt.  So, yes . . . it was started by teenagers.  If you want to see some examples….