Not Looking Back

A man returns home from work early and enters the house through the kitchen door. He sees his wife on her hands and knees scrubbing the floor. She only has an apron on so the husband gets a big hard on, drops his pants and starts humping his wife doggy style.

When he is finished, he pulls out and at the same time hits her hard up the side of her head.
"What was that for?" the wife screamed "Here I am being so nice to you, and letting you enjoy yourself. Why did you hit me?"

The husband looks at her and angrily says, "For not looking back to see who it was!"