I from the US, just learned about these today, and had a chuckle.
an essex girl was driving down the A13 when her car phone rang. it was her boyfriend, urgently warning her “treacle, i just heard on the news that theres a car going the wrong way on the A13. please be careful!” “its not just one car!” said the essex girl “theres hundreds of them!”
The fact that it’s usually women doing the dumb thing is problematic, but these jokes are easily mapped onto whoever you want to denigrate. As a Montana, these were often jokes about North Dakota, and as the scion of a large Norwegian clan, I also often heard these as Sven and Ole jokes.
To me the latter is actually a funnier way to approach them, because it’s two characters who everyone knows are dumb (and who are stand-ins for those people in your life who act this way) and you’re not just blanket insulting a whole group of people.