Q: Why did John jump up and down before drinking his juice? 
A: The box said, “Shake well before drinking!”

Explanation:  Johnny was sooooooo confused!  When the box says, “Shake well before drinking” it is talking about the box, not the boy who is drinking the juice!  Shake the box, Johnny!

Shake, shake hands, milkshake, shake your head, shake and bake, shake, rattle and roll, …