Pump Up the Volume (1990)

In Arizona, an introverted and insightful teenager, Mark Hunter (Christian Slater), finds an outlet for his viewpoints through a shortwave radio. Broadcasting as Hard Harry, Hunter uses his pirate radio show to rant against the injustices and hypocrisies taking place in the area, and in society in general. Hunter conceals his off-air identity, but a determined student (Samantha Mathis) discovers the truth, while Principal Creswood (Annie Ross) seeks to shut down Hunter once and for all.