But I was pretty screwed up at the time, and had to leave. Years later I went to graduate school at the Columbia University School of Fine Arts but I studied prose writing, not film writing.' He earned a Master of Fine Arts from Columbia University in 1995. Louis, Gunn founded a band, The Icons, in 1989, serving as lead vocalist. The group released the album Mom, We Like It Here on Earth in 1994, and its songs 'Sunday' and 'Walking Naked' were featured in the film Tromeo and Juliet. Gunn has continued to work in music, composing songs for Scooby-Doo, Scooby-Doo 2: Monsters Unleashed, and Movie 43. Gunn began his career in filmmaking with Troma Entertainment in 1995, for which he wrote the independent film Tromeo and Juliet.
Working alongside his mentor Lloyd Kaufman, the co-founder of Troma, Gunn learned how to write screenplays, produce films, scout locations, direct actors, distribute films, and create his own poster art. After contributing to several other Troma films, Gunn in 2000 wrote, produced and performed in the superhero comedy The Specials, directed by Craig Mazin and featuring Rob Lowe, Thomas Haden Church, Paget Brewster, Judy Greer and Jamie Kennedy.