how to confuse ghosts

the blending of cultures starts when you see doublegangers; of people you know, but they appear in the wrong setting, on the other continent, in that other city. first signs of homesickness? I am not sure. more the accepting of your new surroundings, circumstances, and you have to reassure you that even this city can feel like home, like the known, the usual, the common.
but sometimes you run into ghosts, actually real people, that you don't expect here and who behave exactly like in this other city, in this particular scene that you know oh so well and that you wanted to escape. what to do? play the game, exactly how you used to because you know it's just a ghost and it will disappear in a second? ignore them? talk English to them (as you know, or you hope this alters not only your timbre but also what you say)? say something completely unexpected (works only if you are a very spontaneous person)? pick your nose (always a good one)?
I opted for the first and felt angry and weird for the rest of the day. How to confuse these ghosts? How can you scare them away?