MORRISON, Colo. (KDVR) – The creators of “South Park,” Matt Stone and Trey Parker, are celebrating 25 years in the business by putting on a musical concert at Red Rocks.

It has been a quarter-century since two unknown Colorado boys started a phenomenon.

“I think it’s the fact that they are not afraid to poke fun at everything. And people need to laugh, that’s been pervasive for the 25 years, it’s never going to go away,” Jeffrey Lesan from Comedy Central told FOX31.

It began with the irreverent “South Park” cartoon, then movies, then music, and now even food with the purchase of the famous Casa Bonita Mexican restaurant in Lakewood.

There is a lot to celebrate. That is why Red Rocks was chosen as a location for the “South Park” 25th-anniversary musical performance.

“When you hear on the show, it’s a little bit children’s sing-songy but when you hear it in practice in here, it’s professional bands, professional musicians, and you realize how actually incredibly complex the songs are and how great they sound live,” Lesan said.

The first concert was on Tuesday night. Every single “South Park” song was performed live by Stone and Parker to a sold-out crowd. A second is taking place Wednesday.

“They are composers. They are people who think about songs and the complex way songs need to be. It’s not just an actual cartoon, there is actually a lot of skill. They are skilled musicians,“ Lesan said.

“South Park,” 25 years later — an irreverent journey into the creative brains of a couple of Colorado boys.