Tenacious D in The Pick of Destiny

As a young man, JB (Jack Black) runs away from his religious family and oppressive Midwestern town for Hollywood after being graced by the word of DIO on a quest to form the world's "most awesome" rock band. There he meets acoustic guitarist KG (Kyle Gass), who is performing on the street, and begins worshiping him as a rock god because of his skills and attitude. JB attempts to ask KG to teach him rock and roll lessons, only to be refused. Later in the night, a crestfallen JB mopes on a park bench, seconds before being beaten up. KG takes pity on JB and agrees to teach him. KG feeds JB's fantasy by pretending to be famous with a self-named band ("The Kyle Gass Project") and exploits him to do work such as cleaning his apartment and buying him weed (under the promise that JB can audition for his fictitious band). After JB learns KG is actually unemployed and living off his parents, the two become equal, and KG apologizes to JB by giving him a brand-new guitar. They create their own band: Tenacious D, named after matching birthmarks found on their buttocks.