Two blonde builders were working on a house.
One blonde was on a ladder nailing. Each time she reached into her nail pouch and pulled out a nail, she'd look at it, and either toss it over her shoulder or proceed to nail it into the wood.
The other blonde watched for a while, puzzled. Then she couldn't stand it any longer and yelled up, "Why are you throwing some of the nails away?"
The first blonde 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 safely!"
The second blonde got very frustrated at this and started to call her all kinds of names. She explained, "Don't throw away the nails that are pointed toward you! They're for the other side of the house!"