Bucket their door some night.

Assuming the door opens inward into their home, this is what you do.

1 Buy a large bucket and some large mouthed containers which can be sealed.

2.1 Collect your urine in sealed containers until you have enough to fill the bucket 2/3rds of the way.

2.2 Collect dog shit and allow for it to ferment with your urine in the sealed containers.

3. Practice angling the bucket with plain water in it against a door.

4. When you have enough urine/shit mash, fill you bucket someplace after you have left your home for sometime. It might be best if your neighbors know/think you have not been around for a few hours.

5. Angle it against your neighbor's door when you know that they are home.

6. Ring doorbell and exit the area.