I was handed a flyer for a restaurant advertising 4 choices of
"Plat Du Jour - of the Week"

hmmm

Well, technically I suppose you can have the same plate of the day for a week, but it is funny.

Or either it means that du jour has come to mean 'special dish not on our regular menu' in English. No reason we have to keep it meaning what it meant in French when we stole it from them. As far as I know it doesn't even mean in French what you think it should mean in English any more.

Did it ever? Or was it always just affected Franglais Restaurantese? I wonder.

In this case, especially as you have 4 to choose from, I think it was definitely affected Franglais Resaurantese which is why I found it funny.

As far as I know it doesn't even mean in French what you think it should mean in English any more.

Mayhaps the French borrowed it from us (link)?

Oh ,I get déjà vus on top a limping computer. Did you not have this before? The plat du jour of the week? It means it will be the same 4 plats du jour all week long. Life is hard....ha, but weeks are short. And ave a ju maiduh jour choixce?

Try again in a non-francais accent, it's a curry house.