How to offend the locals (at the table and away from it...)

First of all, tell them they are locals. I did it in Macedonia. He was supposed to pick me up in the morning to bring me and my (big) suitcase to their office, so I could work for a couple of hours before taking off, back to London. He was born in Skopje, went to school there, still works in the same city 30+ years later.

So here I am. Waiting at the corner of the streets he mentioned yesterday. It is freezing cold. Little do I know that he is turning into a piece of ice at another corner of the same streets. You don't expect one of the streets to be a crescent and crossing the other one twice, do you? Good forty minutes later we manage to meet each other. I am confused, he is unhappy. And then I say:" But you are local..." I learn more than I ever wanted about the Balkan tempers in the next three minutes

I still don't know why. But he took it as an offence. He said "What? You called me local?"
Any advice on why you think this happened will be very much appreciated. Let us know in the comments what it meant to the guy if you think you understand what it was.

Below - more ways to offend the locals. And much more of rather useful information on etiquette abroad. Let us know if you are local (did I say it again?) and you think the advice in this article is not 100% correct.

http://www.telegraph.co.uk/travel/advice/Travel-etiquette-how-to-avoid-offending-the-locals/

TK