The title of this thread cracked me up to start.
I would spray these kids with your water hose...then be like oops I'm just watering the bushes...sorry. They will start to realize that maybe it's not the best place to piss by your property.
Here in NYC the biggest city in the world with no public bathrooms people piss on other peoples property all the time...but if caught you will get a ticket and must show up at court. Kind of ridiculous not to have public bathrooms...when you have 10 million people going out to eat and drink.