Cat

A young daughter had adopted a stray cat.

To her mother’s distress, he began to use the back of their new sofa as a scratching post.

"Don't worry," her husband reassured her. "I'll have him trained in no time."

The mother watched for several days as her husband patiently "trained" their new pet.

Whenever the cat scratched, her husband deposited him outdoors to teach him a lesson.

The cat learned quickly.

Spoiler:

For the next 16 years, whenever he wanted to go outside, he scratched the back of the sofa.