Rock and roll

“	I guess you guys aren't ready for that, yet. But your kids are gonna love it.	”
	— Some guy upon inventing rock and roll

In the 1950s, people loved rolling rocks, so they made a new style of music derived from jazz that is as fun as rolling rocks. It uses sort of the same instrumentation as jazz, but rock and roll songs are more danceable than jazz. Elvis Presley loved that in particular, to the point where he made a living out of it.