The movie is called "The Grinn" because of the creature's face outside Vance's house, which has a large, unnerving grin. The name is an ironic pun because a grin typically connotes happiness, but the creature in the movie represents the opposite -death. This characteristic creates a playful contrast with this subject, an antagonist associated with death. Overall, the pun in the title visually represents the creature's face and generates a sense of irony and contrast.