https://www.youtube.com/watch?v=ubaXd19PkIU
One of the greatest cartoon series of recent years, Adventure Time ran for ten seasons on Cartoon Network. Created by Pendleton Ward, the original short above was produced for Frederator Studios’ Random! Cartoons show and aired on the Nicktoons network on January 11, 2007. Finn was named Pen.
More at the Adventure Time Wiki.