"Gangnam Style" is a Korean neologism that refers to a lifestyle associated with the Gangnam district of Seoul, where people are trendy, hip and exude a certain supposed "class." Literally translated from Korean it basically means older brother style or rich old guy style. It is not English but Korean.

It's a new dance craze http://www.youtube.com/watch?v=9bZkp7q19f0

I think your meaning is related to South Korean rapper PSY’s “Gangnam Style” video which has 220 million YouTube views and counting, and it’s easy to see why. No Korean language skills are needed to enjoy the chubby, massively entertaining performer’s crazy horse-riding dance, the song’s addictive chorus and the video’s exquisitely odd series of misadventures. Beneath the antic, funny surface of his world-conquering song, however, is a sharp social commentary about the country’s newly rich and Gangnam, the affluent district where many of them live. Gangnam is only a small slice of Seoul, but it inspires a complicated mixture of desire, envy and bitterness.

It's Korean for "condom store".