Do you mind if I…?
When I’m asked a question starting from this sentence in person, I always get nervous a bit. Because even when I do want to tell that I don’t mind, I often ended up telling them “YES!” with a big smile and make them puzzled.
I guess this is because I automatically translate this sentence into Japanese in my head, and reply with Japanese way. This is tough to explain only with English but when you ask “Do you mind if I sit here?” in Japanese, we reply “Yes, I don’t mind” when you want to say No.*
Same thing goes to negative questions. When you’re asked “You don’t like pizza?” in Japanese and if you want to say no, you say “Yes, I don’t like pizza.” If you like pizza, you say “No, I like pizza.” This Yes/No works like affirmation and negation of the whole sentence. “You don’t like pizza?” “Yes (=that’s right), I don’t like pizza” or “No (=that’s wrong), I like pizza.”
Though I always could manage to tell what I really meant in the end, this is still tricky question for me to be honest. Most of the people were fine and forgave my mistake with smile, but few got upset and walked away. And a couple of times I was told “you must be Japanese!” so I think I’m not the only Japanese who makes this oops.
*Note: When you translate this as “… shitemo kamaimasenka?" Standard translation. Maybe this causes the issue. If we learnt this sentence with a translation like "Do you get upset/annoyed if I ...?" we could've avoid this problem. Hm.