system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do elementary school kids all over the country know the same playground songs/rhymes/etc?

Edit: Thanks for the responses. It makes sense to me how formal songs and things (Ring Around the Rosie, etc.) would be spread by teachers and media, but what about stuff just perpetuated by kids? Why do kids everywhere say "na na na na na, you can't catch me!" to the same rhythm, or sing "Joy to the world that Barney's dead"? I tutor 1200 miles from where I grew up, and a few weeks ago I had a kid come up and say, "Okay, say "I," and then spell 'cup'!" Is it really just the few who share with friends/relatives in other places that spread it to the rest of us?
gpt
Memes were around thousands of years before there was an internet, and they spread ~~geometrically~~ ~~exponentially~~ quadratically.  ~~This means that one person tells ten people, each of whom tell ten people, each of whom tell ten people,~~ (up to a saturation point? Who even knows how quadratic growth happens?)

(But however it happens,) Within a few years, you have global coverage.