Answer:
A biker's helmet is often called a brain bucket. Not wearing one is literally, "a no brainer." The pun also implies that one riding a bike without a helmet has no brains.
Explanation:
I'm not sure if you meant "The boys are pulling the rope" or "The boy is pulling the rope" but the answer is either "The rope is being pulled by the boys" or "The rope is being pulled by the boy" respectively.