"I said it before and I'll say it again..."
I get the impression that the migrant couple's crash scene is meant to be a "cameo" in the same sense that the Jack Benny, Jerry Lewis, and Three Stooges moments are, in which case the featured comedian is immediately recognizable to the audience. The way his appearance is set up, I'm guessing the featured comedian, Nick Stewart, would have been as familiar to audiences in the same way?
Now, I don't know too much about Nick Stewart only that he was prominently featured on the once popular, now-banned Amos 'N Andy show, which I have only seen snippets of, but was the "I didn't want to move to California" line supposed to be some kind of "inside joke" that the audience, at the time, would have gotten (perhaps an Amos 'N Andy reference)?
Obviously, on the one hand, its just a deadpan reaction to getting driven off of the highway by a bunch of reckless mad-cap "Californian" drivers, with all of their stuff getting scattered down the hill. But, I feel like part of the joke just went "right over my head"
To people more familiar with Nick Stewart - did I miss something?