Why are rocker panels called rocker panels? The name suggests something that moves. But, they don't move anymore than any other part of the part of cab.... And, they aren't really panels, any more than an inner fender or door post are panels. I suspect that this all goes back to the days of horse drawn buggies. Anyone know?

 

Here's what Wiki says about them...

Rocker
The body section below the base of the door openings sometimes called the "rocker panels", or "sills".

But it doesn't give the origin. Maybe if you were stuck high centered on a bump or rock, it would be where the car would "rock" back and forth?

 

Jolly Roger Joe, you rock!