The Lawn Ranger is a play on words referring to The Lone Ranger, a masked cowboy crime fighting hero of the old west that was a black and white TV show when I was a child in the 60s. The Lone Ranger was like a self-appointed "Sheriff", righting wrongs everywhere he went.
Basically, my neighbor is mentally ill, doesn't work, is bored and has chosen my family to pick on. He does elaborate yard work daily and has a spectacularly beautiful lawn so he gets angry and acts out in bizarre ways if your lawn doesn't look like his lawn. So, my neighbor is The Lawn Ranger, lawn referring to the grass around his house. He is the hero to lawns everywhere, fighting to keep them weed-free even when the lawn belongs to lazy folk like me and my husband LOL. For instance, my neighbor waters his grass daily and cuts it 3 times a week. We let rain water our lawn and cut it once a week unless we're in a draught and the grass doesn't grow.
Hope that made sense.