Two dimwitted brothers were putting the siding on a house. One takes a smoke break watching the other one work.
The other brother is pulling one nail from his tool belt and driving it home, pulling out another one looking at it, and tossing it over his shoulder, another into the siding, another over his shoulder.
The one brother, perplexed at his brother's odd and wasteful behavior struts up to this obvious dimwit and asks why he is throwing half the nails over his shoulder.
"The pointy sides were on the wrong end!"
"You Idiot!!!!!!" " Those are for the other side of the house!!!!!"