These are the jibes that I hear every week, which have caused me a great deal of hard feelings:
“Where are you REALLY from [after you tell them the town/county you live in]?”
“You don’t look like White. Are you really British? How many years have you been here actually?”
“Your English is brilliant! Where are you REALLY from?”
“XXX has a British passport, BUT he/she comes from...”
“Nationality is not the same as ethnicity. Just because you are a British citizen, it doesn’t make you automatically British!”
...