Cute Question, Catastrophic Consequences

(I am of Eastern European descent and many languages from that area have similarities. Two women come to my counter speaking a language I can somewhat understand.)

Me: “Good day! Can I ask where you’re from? I can understand a few of the words you were saying.”

Customer: “Where are you from?”

Me: “I’m from [place], part of former Yugoslavia.”

Customer: “Guess where I’m from!”

Me: “Oh no, I can’t. I’m pretty bad at guessing that sort of thing.”

Customer: “Guess!”

Me: “No, no. I’ll get it wrong. Never mind.”

Customer: “Just guess! Who cares if you get it wrong?”

Me: “I don’t want to insult you if I’m really off in guessing.”

Customer: “Just try! I’m not going to get mad!”

Me: “Okay, are you from Serbia?”

Customer: *angrily* “Serbia?! I should beat you for such an insult!”