> I ordered a cheeseburger in Spanish and the server looked at me funny when I said: ”hamburguesa con queso sin pepinillos…”
Yes, I agree that replying to a stranger in his mother tongue may make him extremely surprised.
A couple of months ago, I was in an Arabic country (in the Gulf), I entered a small shop to buy some stuff, the shop owner was obviously Hindi/Pakistani, I asked him about the price, in English of course, he replied then I asked for a possible discount if I bought in bulk and set my willing-to-pay price, he resisted then I smiled and said "yie bohot acha price hain", and he (and his assistant) were shocked like they were hit by a 380v electric shock. They stared at me and said: "tu tu tum bolo hindi?!" I replied,"nai bhai, tora tora. ".. he laughed and agreed immediately to the price I offered.