What would you do if your neighbor allows their dog to poop on your lawn and not clean it up?

If the neighbor is aware of what their dog is doing, like I would catch them staring at the pet do their droppings in my lawn, then I would not be so nice. I would say it in that same moment they are delighting themselves with such beautiful view something like "put a leash on your dog and take him some place other than my lawn to do his necessities but being that you are enjoying yourself so much, why don't you take him in your living room and have some pop corn while watching". geeezzzz