Ron and John were building a house. John was on a ladder, nailing. He'd reach into his nail pouch, pull out a nail, look at it, and either toss it over his shoulder or proceed to nail it into the wood.

Ron couldn't stand it any longer and yelled, "Why are you throwing some of the nails away?"

John explained, "When I pull it out of my nail pouch, if it's pointed toward me, I throw it away. If it's pointed toward the house, then I can use it."

Ron replied, "What's wrong with you? Don't throw away the nails that are pointed toward you! They're for the other side of the house."