Two blondes were repairing a roof

Two blondes were repairing a roof, with one working on one side and one on the other.

After a while, one blonde noticed that her friend would carefully examine each nail before hammering it down, but half of the time she would toss the nail behind her after examining it.

Figuring that there couldn’t be that many bad nails, she yelled out to her friend:

“Why are you tossing out all those nails?”

“Well, those were all pointing the wrong way!” was the response.

Infuriated, the first blonde bellowed “You, idiot! Those are for my side of the roof!!”