A man and his son were walking down the street one day. They saw two dogs having sex in a yard.

The son asked his father, "Daddy, what are they doing?"

Thinking fast, the father said, "Well, son, they are making puppies."

Every thing was okay for a couple of days. Then, one afternoon, the father was making love to his wife when the son walked in.

The son asked, "Daddy, what are you doing?"

Thinking fast, the father said, "We're making you a baby brother."

The son thought for a moment, then said, "Well, roll her over, daddy, I'd rather have a puppy!"