The Illusion of Explanatory Depth
You think you know how a toilet works. Try to explain it. You don't.
Grounded in the research on Illusion of explanatory depth (Wikipedia)
What it actually is
The Illusion of Explanatory Depth (IOED) is your brain confusing familiarity with understanding. You can picture a toilet, a zipper, a bike, the economy, so you feel like you get how they work. You don't. You only know what they do, not the causal mechanism. Coined by Yale researchers Leonid Rozenblit and Frank Keil in 2002.
The experiment that proved it
Rozenblit and Keil ran it clean. Step 1: rate how well you understand everyday devices, 1 to 7. Step 2: now write a detailed step-by-step explanation of how one actually works. Step 3: re-rate yourself. Confidence dropped every time. The act of explaining forced people to hit the wall of what they didn't know. Knowledge they were sure they had evaporated on contact.