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Leon the Pole and his friend Jan are building a house .
Leon is putting on the siding. He picks up a nail, hammers it in. Picks up another
nail, throws it away. Picks up a nail, hammers it in. Picks up
another, throws it away. This goes on for a while, and finally Jan comes over and asks him why he is throwing half of the nails
away.
He replies, “Those were pointed on the wrong end.”
Jan gets exasperated and says “You idiot, those are for the other side of the house!”