“We had to pretend we were back when we were 13 and believed in movies, because we’ve been in this Hollywood world,” Armen Weitzman says when describing his new comedy, “ The Napa Boys .” Weitzman co-wrote and stars in the film, which delights in spoofing tired Hollywood storytelling and franchise fatigue, while toggling between jokes that are exceedingly clever and thrillingly dumb. All humor is welcome as a result of the mind-boggling concept: In the film’s reality, “The Napa Boys” is a long-