A few short months ago, no one really knew who Psy was. Now, he's performing on stage with the likes of Madonna.

You know you're a superstar when Madonna does a rendition of your song, just ask Don McLean. For the second night in a row, Madonna played New York City's Madison Square Garden. For her second performance, she had a special guest, Psy.

Her and Psy got their 'Gangnam Style' on, and the crowd loved it.