John Oliver followed last week's episode-long critique of Donald Trump on HBO's "Last Week Tonight" by dedicating this week's episode to special districts.

Yes, Oliver knows the topic isn't sexy. "Hello, people watching for the first time because of our Trump piece. And, also I presume, goodbye ... Thanks for checking in," he said by way of introduction.

The thing is, the show does a great job of explaining why Americans should care about special districts, which Oliver defines as "small units of government with the power to use tax dollars to do one specific thing."

As the host explains, most of us are aware of water districts or fire districts, but there are way more special districts than most people know about. Oliver refers to them as "ghost districts." There are about 40,000 special districts in the US, and they spend about $100 billion a year, one expert said in a clip.

"That is 16 billion more than Russia spends on its military," Oliver said, before pointing out that, school districts included, special districts are the most common form of local government in the country.

"Harold!" "Last Week Tonight"/HBO

"That's crazy," Oliver began a tirade. "It's like finding out that the highest-paid athlete in the world is Harold. I mean, who the f--k is Harold? What sport does he play? Why don't people talk about this all the time? How am I only hearing about Harold now? You're making me feel a fool!"

In fact, these special districts can operate with very little oversight. As an example, Oliver points to Idaho, which did a study of special districts. Its first priority? To find out how many the state had. The state government didn't even know. Another study on special districts conducted by Kentucky found that 40% of these "local governments" didn't even file budgets as they're legally supposed to do.

So, again, how does all this special-district tomfoolery affect you? Oliver points out that Americans could be living in 10 or more special districts and not know it. And what could that mean? One example: An expert explained that one person in central Phoenix paid $1,000 in taxes while his neighbor belonged to a different district and paid just $7.

"Look, the only people who should be spending a thousand dollars more than their neighbors across the street are the a--holes who are covering every square inch of their house with Christmas decorations," Oliver said. "They should be taxed. And then, they should be imprisoned. And then, they should be told their lights were better last year, because it's that one that would hurt them the most."

Find out more about how special districts affect you in the video below: