I saw this movie with my dad when I was younger. Its an old black and white WWII spy movie. The guy is an American (possibly British) and he is undercover in enemy territory. He ends up at this Tavern/Pub type place. He needs to wait for something there, a person or some sort of info. So he sits down and orders food. He ends up getting caught/revealing himself because of his eating habits. He switches the utensils in his hand from when he is cutting his meat to when he eats it. Germans don’t do this. So everyone knows he is an American. I know he gets away from that place. I can’t remember the name of that movie or any of the actors in it. I remember it was a GOOD movie and I want to try and track it down. Its driving me crazy.  It was made probably in the 40’s or 50’s, possibly the 60’s. But I would say no later than that.