South Park Episode 405 - "Cartman Joins NAMBLA"

Cartman decides to seek the friendship of older men. Using the Internet, he makes a connection with men who love to hang out with little boys. An organization called NAMBLA (North American Man Boy Love Association) holds a meeting in South Park and Cartman becomes their poster child. The boys learn how much an adult can really love a child.

http://www.southparkstudios.com/guide/406