This is something you're making uppolenta might have been expressed (my personal inspiration for the word polenta in this particual context ) to the slowness he takes to hurry up, as the polenta, a tipical Italian dish, takes quite a lot to cook
Sorry Fooler, but I cannot agree. Slowness has nothing to do with this expression; there are a lot of "mannaggia" together with nouns / names, see my post #7. You can replace "la polenta" with many other terms (la miseria, li pescetti, la marina, or even worse...)
It can be useful to read here: 6 sfumature di ‘mannaggia’ | Modi di dire napoletani
This is something you're making up
You could change polenta a hundred different words and this expression would mean exactly the same thing.
Not too much... And you remember correctly, yes.A friend of mine used the version (if I remember correctly ) Mannaggia a tua nonna in carriola!. I think they all sound a little silly, to be honest.