Seriously?

I understand that English may not be your first language. Don't get me wrong, I think that's really cool to be bilingual, or trilingual, etc. But in mixed company, could you stick to English, please? Or at least translate what you are saying?
Why?
It leaves the rest of us out, and quite frankly, it's kind of rude. When you're speaking to friends and all of a sudden you switch to a language that not everyone speaks it ostracizes people, and it leaves those of us monolinguals slightly bitter.