Tenacious D: The Fan (1999)

Synopsis
It's open mic night again, and the fellows perform "Explosivo" for a mostly unsympathetic audience. Jack (Jack Black) throws a bunch of picks into the crowd as a celebratory gesture during the song, but he mistakenly loses his special clear pick in the process. After hours of searching to no avail, creepy loner Lee (Jason Reed), the band's self-proclaimed biggest fan, reveals that he's recovered the pick. Jack and Kyle (Kyle Gass) are spooked by Lee's stalkerazzi weirdness, but that doesn't stop them from rushing to check out the website Lee has created in their honor. The guys decide to turn the tables on Lee, following him everywhere, breaking into his apartment, crafting a theme song for him, and even murdering him in a dream montage. Lee adores the attention, and he joins the D on-stage at open mic night, where he shares lead vocals with Jack on the tender "Special Things." ~ Tim DiGravina, All Movie Guide