Wow, I love this - I lived in Korea for about 18 months and can pick up a fair bit of the culture specific messages.
For some reason, none of the translations I've seen cover the term "Oppa", which is translatable and kind of important to get the song's meaning. "Oppa" (as I understand it, and I might not be 100% correct) is used by girls to refer to an older male friend, and so "Oppa (nun?) Gangnam style" would mean something like "Daddy's got Gangnam Style", with "daddy" used in the sense of "sugar daddy". At least that is my interpretation and I'd like to see any native Korean speakers comment on this.
Between "Oppa" and "Gangnam" is the Korean topic particle[0], "는" ("neun"). Your translation is basically correct.
"Oppa" is the word traditionally used by women to refer to their elder brothers, but younger Korean women have started using it to refer to their boyfriends/love interests as well[1], although it can also be used between non-blood relatives in a totally platonic manner (which can lead to plenty of ambiguity about romantic intentions, which a lot of people of course thrive on).
For some reason, none of the translations I've seen cover the term "Oppa", which is translatable and kind of important to get the song's meaning. "Oppa" (as I understand it, and I might not be 100% correct) is used by girls to refer to an older male friend, and so "Oppa (nun?) Gangnam style" would mean something like "Daddy's got Gangnam Style", with "daddy" used in the sense of "sugar daddy". At least that is my interpretation and I'd like to see any native Korean speakers comment on this.