It happened to me twice and I didn't realise I was damned until later.
First incident happened donkey years back when I re-contracted my mobile with Starhub. When the deal was done, the staff handed me a green umbrella stating that it was a gift. Smiling as I was happy to get something free, I asked, "Do you have any other colour ..... like red?" He gave me a sort of unhappy look when he answered "No, only green". I thought it weird so I just murmured something like thanks and never mind. It only dawned on me after I got home that he must had thought I was trying to be funny. Of all the colour I mentioned red.
Second incident happened when I was on holiday. I was in the hotel lift when a group of tourists with their luggage entered and filled it to capacity. They had just check-in and were going to their rooms. As they had trouble using their cards to get to their floors, I helped and the conversation started.
Me: Are you Japanese?
Someone in the group: No, we are from Korea.
Me: Oh, I thought you are from Japan cos it sounded Japanese.
Another person in the group: No, not Japanese. We are Koreans.
Me: I see, Korea, North Korea or South Korea?
All eyes were staring at me and there was an eerie silence.
Me (oops and ): Seoul? Are you from Seoul?
The tension eased and some of them nodded: yes, yes, Seoul