Randall Munroe, author of the xkcd comic strip, is a geek hero. Not only do his cartoons include maths, science and computer programming, he doesn't dumb them down for a mass audience. You're expected to understand mathematical symbols and jokes that revolve around logic... though there's an Explain xkcd Wiki if you don't.
However, Monroe's latest large-format book - Thing Explainer: Complicated Stuff in Simple Words - uses the reverse process for humorous effect. It's a "how stuff works" book that explains things using only the thousand most common words in the English language. Which means translating complex concepts into extremely simple words.
You can understand the scale of the problem when you realise that Monroe isn't able to say "thousand most common words" because "thousand" isn't one of them. His explanations can only use the "ten hundred" most common words.
The book was inspired by an xkcd cartoon about the giant Saturn V rocket, which became the "Up-Goer Five" because the rule wouldn't allow him to use words like "Saturn" or "Rocket". It includes labels like "breathing-type air (for burning)", "the kind of air that once burned a big sky bag" and "that kind of air that makes your voice go funny".
Many of the captions are humorous. For example, at the end of the Up-Goer Five rocket where the fire comes out, Monroe notes that "This end should point towards the ground if you want to go into space. If it starts pointing towards space you are having a bad problem and you will not go to space today."
Monroe first used Up-Goer Five when playing a game, Kerbal Space Program, which involves building and flying rockets. It wasn't from his time at NASA, because he was working on robotics, not on rockets. He explained all this during his book tour talk at the Space Center in Houston, which I watched via a live video link. Apparently that was his first chance to see a real Saturn V....
Of course, Thing Explainer covers a much wider range of topics. Some are relatively simple objects, such as writing sticks, picture takers, and food-heating radio boxes. Some are complicated, such as hand computers, sky boat pushers (airplane engines) and machines for burning cities (atom bombs). Some are biological machines, like the tiny bags of water you're made of, and the bags of stuff inside you (blood pusher, yellow water holder etc). Some are almost impossible, such as "the pieces everything is made of" (ie the periodic table).
It turns out that even if you know the technical name for something, you don't necessarily know exactly what it does. Thing Explainer works backwards: you learn what something does, then figure out the technical name. The more obscure ones are obviously more satisfying.
I started out thinking this book was going to be a sort of "Explain like I'm Five" (ELI5) with funny drawings. It's not. It's more like a puzzle game, and quite often enlightening.