How do high schools create chants?

I'm only asking this because a new high school was built near where I live recently and it got me thinking, how are the chants created in the first place? For me, my school has a chant whenever we all get together and have a great time, and when it's over but the hype is still there, we chant "Ain't no party like a Wildcat* party" *I'm not putting our actual mascot there but that's an example. Does anyone know because I surely don't.