What are some fun ways to prank an asshole neighbor I'm moving away from?

Not really me. A friend of mine is moving out of state. His neighbor has been a total dick the entire time he's lived there. Constantly commenting on how my friend's yard isn't as good as his. Mean to my friend's wife and kids for no reason. Just an asshole of a person.

What are some ideas for fun pranks my friend can leave behind?