You know that feeling you get sometimes, that people are talking about you or keeping secrets behind your back? You probably felt it the most when you were between the ages of 11-13 when everyone had secrets that you weren't included in. Most of the time it was just your imagination and there was probably someone else saying the same thing about you, on the other hand, if you're a woman, chances are some of those girls really were being mean. We can't help it and it's a sign that you've started growing up when you realise that you are-unintentionally- hurting people around you and you begin to reign in some of those comments. Not all the time though, sometimes saying those couple of comments to someone who you know will agree with you is all that gets you through the day!! So imagine the frustration of people who walk into a room to find people speaking a language you can't understand and not feeling welcome to share in a conversation.
Being considerate and switching languages won't endanger your national identity or language, nor will it make you look like a show off to your fellow countrymen, who knows, you might even enjoy talking to someone with a different point of view. You could even learn something and broaden your views.