Nimrods isn’t a typical band movie. Although the project is being billed as “a Green Day comedy,” its three members, Billie Joe Armstrong, Tré Cool and Mike Dirnt, are not the main focus of the project; instead, the film is a coming-of-age road trip story about three buddies who drive across the country when they’re pranked into thinking their band will open a New Year’s Eve show for Green Day. “I always wanted to have a movie that was like we were in the background of it and it’s kind of based on the music conducting the whole narrative,” frontman Armstrong told The Hollywood Reporter at the L.A. premiere on Wednesday. “I love like Rock…