My son loves this song (still). He sings along with it, and told me that “yoja” probably means girl and “sarae” probably means boy. We are listening to it right now, and he says things like “I wonder what that translates as.”
I asked him if he wished he spoke Korean and he was noncommittal. But he does like the song very much…and you have to admit it is catchy!
A link from the comments….apparently “Gangnam” is a tony part of Seoul. http://www.theatlantic.com/international/archive/2012/08/gangnam-style-dissected-the-subversive-message-within-south-koreas-music-video-sensation/261462/