There were three women who always hang their laundry out in the backyard. When it rains, of course, the laundry always gets wet - all the laundry, except for Sophie's. The other two women wonder why Sophie never has her laundry out on the days that it rains.

So one day, they are all out in the backyard putting their clothes on the line when one of the women says to Sophie, "How come when it rains, your laundry is never out?"
"Well," says Sophie, "when I wake up in the morning, I look over at Paul. If his penis is hanging over his right leg, I know it's going to be a great day and I can hang out the wash. If his penis is hanging over his left leg, I know it's going to rain, so I don't hang out the wash."
"What if it is pointed up?" asks one of the women.
"Honey," says Sophie, "on a day like that, you don't do the laundry!"