Madonna's world "MDNA" tour made another pit stop in New York City on Tuesday in Madison Square Garden, and this time the Queen of Pop wasn't alone.

Madonna teased that she would treat the audience to a special surprise guest during the show, and after much anticipation, she revealed it to be none other than Psy, the artist behind the breakout viral hit "Gangnam Style."

Psy, who flew to New York City from Frankfurt, Germany, for the occasion, wore a bold and shiny red suit as he and Madonna performed "Gangnam Style" together, with Madonna and her dancers even doing Psy's "horsey dance" from the video for his song, which has attained more than 722 million views on YouTube.

After performing Psy's hit, the pair added another surprise song to the night's set list — Madonna's huge hit from 2000, "Music." The Material Girl and Psy danced together throughout and seemed to be having a great time, as was the crowd packed into Madison Square Garden.

Check out the video below to see Madonna and Psy perform "Gangnam Style" together.

The "MDNA" tour began this summer and has been well-received by fans and critics alike. The world tour is on track to become one of the most profitable tours of all time, with some reports estimating revenues of $300 million.

The show includes performances of some of Madonna's biggest hits, including "Vogue," "Like a Prayer" and "Express Yourself," but the Material Girl's performances have drawn more attention for their violent images and Madonna's antics, including flashing her breast and projecting swastikas over the face of a French politician.

During her Sept. 6 performance at New York's Yankee Stadium and several tour dates afterward, Madonna got political and gave a shout-out to President Barack Obama. As she stripped down during a performance of "Human Nature," the Queen of Pop revealed big, bold letters bearing the word "OBAMA" across her back.

"Thank God for Michelle Obama and her good-looking husband, too," she said to deafening cheers.

Tags: Madonna psy gangnam style