In our family the subject of porta-potty cleaning often comes up around Thanksgiving or Christmas. Generally it's one of our three sons who brings up the topic while the family's together and, has families are known to do, talking about the old days.
Here's how it might be introduced into the conversation..."Yeah, remember when Dad gave us the porta-potty warning..." The speaker would be referring to a time when the three of them were in the back seat as we motored smartly along some interstate highway somewhere. As I was passing a truck on our right one of them asked what kind of truck it was, meaning what it was used for as he'd never seen one like it before.
I explained that it was used to clean out porta-potties, pointing out the big hose wrapped around a motor/pump device, the large holding tank and whatnot, and explained it was the driver's job to go around and suck all the stuff out of however many potties on his route.
From the back seat came a reply along the lines of, "Yuk! Who'd wanna do that?"
Well, I know a teaching moment when I hear one so I went on to explain it was one of the more crummy jobs a guy could have but the people who do it didn't have much choice because they didn't apply themselves in school and thus they're not qualified to be hired to do much else in life. Ended it with a very Ward Cleaverish, "That's why Mom and I are always telling you guys how important it is that you work hard in school."
Don't know how much that lecture had to do with it, but all three did very well academically in grade school and beyond.