Am I being a sterotype? Was I to mean to the girl?

Your friend is right. What you said was thoughtless. Thought - less. Meaning you did not think. Get to know lots of people and don't hate anybody because of what they look like. You wouldn't want people to say "I don't like Puerto Ricans and I don't talk to them" It would be very insulting. I'm just glad you have a good enough friend to be hoinest with you. Now don't make the same mistake again. As for the other girl if you see her again just give a simple "I was thoughless" apology and DO NOT try to defend what you said. it was wrong. PERIOD.