A principal physically attacked a student for advocating a GSA in school in Tennessee:
Chris Sigler wore a homemade T-shirt to school last Tuesday that read, "Gay Straight Alliance: We've Got Your Back," according to the American Civil Liberties Union, which is assisting Sigler and other students in the matter. Though he was told to cover up his shirt that day, he wore the shirt again the following Friday.
Principal Maurice Moser came to Sigler's economic class in the middle of an exam, and demanded that all other students leave the room. Sigler's sister Jessica refused to leave. Both siblings said Moser grabbed Chris's arm, shoved him against a wall, and chest-bumped him several times, while asking, "Who's the big man now?" The attack ended when Sigler's mother arrived at the school to find Moser leaning over her son, shouting in his face. Moser eventually agreed not to formally suspend Chris, stipulating that the student leave the school grounds for the remainder of the day.
From what I've read, it isn't clear if the principal got violent because of the gay issue or an authority issue. In schools it's important to maintain order and a principal, many of whom have never been teachers and often don't have much experience handling willful disobedience, might get frustrated because he doesn't have the skills necessary to handle such a situation. (I don't know this principal's work history; he might just be out of control.)