Someone handed me a flyer for a local restaurant today advertising the "Plat du Jour of the week"

Ha! though it's clear what they mean it is real funny.
How about the " Week Menue du Jour"?

That's pretty funny, but when you mug other languages in dark alleys and rifle through their pockets for the odd word or phrase, I don't believe there's any rules say what you can or can't do with those words or phrases.