Sven and Ole decided to put new siding on the farm house. They were hard at work, nailing on the new siding, when Ole noticed Sven was tossing about every other nail away. He'd pull the nail out of his carpenter's belt, look at it, and either nail it in or toss it over his shoulder on the ground.
"Sven," says Ole. "Vat da heck are ya doin over dere? Vy are ya tossin out all dem dere nails?"
"Some uh dem are made wrong," says Sven. "I pull out da nail, look at it, and if da nail points t'ward da house, I nail it in. If it's made backwards, and points da other way, I throw it out. Aint you doin' da same?"
"Oh Sven, vat da hey??" yells Ole. "Dem dere nails ain't made wrong, ya big goof. Dey're for da other side of da house!"