Brad Paisley took a pause from his Beat This Summer Tour to hit up 'Late Night WIth Jimmy Fallon,' where he teamed up with the funnyman for a duet of the "protest song" called 'Balls in Your Mouth.' Trust us -- it's not what you think!

The host pointed out that a few years ago, he wrote a protest song about the tarballs the that washed up along the Gulf Coast after the BP oil spill. Fallon read an article about how tarballs are still washing up onshore, forcing him to consider reprising the song. He was going to perform the song a la carte, but then he protested his protest song and refused to play it. That's when "country music superstar Brad Paisley" offered to take up the task.

With his acoustic guitar in hand, Paisley took the stage to sing the parody about not swimming in the south unless you want (tar)balls in your mouth.

Fallon dressed for the occasion, donning a black cowboy hat as he grabbed a guitar and performed with Paisley on stage and in the crowd. What an old-fashioned country duet, and it was not only hilarious -- it was also interactive. House band the Roots and the audience sang along and harmonized to a joyous song about a crappy situation.

Paisley also performed his song 'The Mona Lisa' from his latest album, 'Wheelhouse,' in his familiar uniform of white cowboy hat, T-shirt and jeans. For several minutes, the late night show's New York City studio became your favorite watering hole down south.

It was certainly an electrified performance, and not just because the singer was playing electric guitar. When Paisley wrapped the rousing delivery, Fallon said, "That's how you do it." We can't disagree.

Watch Brad Paisley Perform 'The Mona Lisa' on 'Jimmy Fallon'