1. Ask about Kosovo.
If you want to piss off a Serbian quickly and irrevocably, just casually raise the question over the region’s independence. This matter is not something to be taken lightly. When it comes to Kosovo; our nation is divided between ‘Kosovo is Serbia forever’ people, ‘Can we just forget about it and get on with our lives’ people and those who actually lost someone in the riots. You can never be sure what group your interlocutor belongs to before you hit the nerve.