Watch Smarter is Slate’s series that teaches you to spot hidden tropes in pop culture and beyond. Watch all episodes.

We all know what the scrambling cartoon caveman in The Flintstones sounds like, or the sound of a roadrunner sticking out his tongue. But these classic cartoon sounds don’t exist in real life. Where do they come from? How did somebody settle on a sound that’s so different from anything in the real world?

In this episode of Watch Smarter, Slate’s video series about hidden tropes in pop culture and beyond, we trace the surprising history of cartoon sounds we all know but have never quite understood. Our story begins with live orchestras in the 1920s and ends, more or less, inside a coke bottle.