So here are on the top of my head the most common Frenglish catch phrases that you may encounter from time to time and how they are sometimes quite removed from their original meaning:
a la carte, carte blanche, amuse bouche, au naturel ( that means naked here, why I am not so sure), bon voyage ( sometimes used in a sarcastic ways for good riddance, very popular now), clichE, (wine ) connoisseur ( that's the the correct spelling, it's not a word in french but who cares about such details ? ), coup ( for coup d'etat), deja vu ( all over again ) (this one always gets me ), femme fatale, menage a trois (only the physical act), piece de resistance, risquE, touchE, double entendre ( double sens, I think), maitre d' ( maitre d'hotel), encore (only in theatre, you saucy mint !).
So they are mostly either related to food, or sex. That's "l'art de vivre", I guess.