I was in a grocery store with my friend and his mum once, and my friend was trying to do an Indian accent. Specifically Apu's "Thank you come again" line from The Simpsons. His mum told him to stop and later said he shouldn't do that stuff in public. My friend has also done African-American accents in the past and was told he was being racist. I didn't understand why, as being English and going to an American school whenever someone finds out I'm English or hears me say something differently, they always try and immitate an accent or a classic quip such as "governer" or something about tea and biscuits. I've never found it offensive, and niether has any passing adults at the time. I don't understand how immitating one accent is seen as racist, while the other is a common joke. Hell, the school one did a production of Sweeney Todd and every single person did a semi-bad English accent all the way through. No one had a problem with that. It's either all accent immitations are bad, or all are okay.