A little boy and his father are walking down the street, and they see two dogs having sex.
The little boy asks his father, "Daddy, what are they doing?"
The father says, "Making a puppy."
So they walk on and go home.
A few days later, the little boy walks in on his parents having sex. The little boy says, "Daddy, what are you doing?"
The father replies, "Making a baby."
The little boy says, "Well, flip her around! I'd rather have a puppy."