Is the Light On? 

Billy and Johnny are arguing about how tough their fathers are. Billy says,
"My Dad is tougher than your Dad."

Johnny says, "No, my Dad is tougher than your Dad. My Dad is so tough he
can eat light bulbs."

Billy says, "Your Dad can't eat light bulbs. Nobody is that tough."

Johnny says, "My Dad can, I heard him tell Mom the other night that if she'd
turn out the light, he'd eat it."