A father was walking with his young son in the park when they came upon two dogs having sex. The boy asked his dad what the dogs were doing. He said that they were making a puppy.
A couple of days later the boy walked in on his parents who were having sex on the couch. He asked his father what they were doing. He said that they were making a baby.
The boy replied, 'Can you turn Mummy over? I'd much rather have a puppy.'