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).
Comments
> "Oppa (nun?) Gangnam style"
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).
0: http://en.wikipedia.org/wiki/Korean_particles
1: http://askakorean.blogspot.com/2009/06/ask-korean-wiki-oppa-...