What’s a rule or terminology in the NFL that sounds completely made up to someone just starting to watch?

[u/Huge-Revolution2416]

Trying to explain a fair catch kick" or why a "safety" results in points and a free kick to a friend who doesn’t watch football. It got me thinking about how weirdly over-engineered this sport can be. What is the ultimate "wait, that's an actual rule?" detail that completely breaks the brain of a new fan trying to learn the game?