Re: Not trying to be PC, actually anti racist
Stereotypes. Racism. Same? Probably. The issue arises when we find ourselves commenting to make ourselves look better or actuallly consider ourselves better than "x"-group of people.
I live in a predominantly white part of the US. We have a few black kids in the church youth group. We have shared jokes about tanning and some other things - no one has been offended. It is just clear that they are black, and I am white! Black or white isn't the issue however: they issue is that these students are clearly different than most of their peers here, and it happens to be skin color. But whether they are black, brown, asian, russian, whatever- doesn't make them inferior to anyone else. They are accepted- and they accept others- equally.
Strangely, I have experienced prejudice. But not based on color. I lived in Greenville, SC area for about six months once. Some people were fine, whites, blacks. But a large cross section of white people treated me and my wife pretty poorly because we were from the north- yankees. I was threatened when applying for jobs, and had a number of threatening comments made to me about being a yank and called a "******-lover." A guy I got to know a little where I was employed said it all: He said to me once: "Man I admire you. You're brave and you just take it!" I asked him to explain. He responded "Well, you know they hate us, but they want to kill you..." He was a big black guy about 6'4" He was a good guy- wish I had kept in touch.
I moved back north shortly thereafter, concluding I wasn't going to get past the job experiences on my resume which pegged me as a "yank." Now I am not pigeon-holing southerners- a met a lot of decent white people, but it sure did show me what prejudice was.
Identifying with your "brown" girlfriend like you did/do is probably going to preserve your relationship just fine. You can't change ignorant people's opinions and stereotypes, but maybe they will learn something from you guys over time.