Incident at Public School 173 (2012)

This is the movie where a large food fight in a middle school has war zone sound effects (gunfire and mortar blasts), where factions use desks to erect fortifications and where the participants do not get back up after being struck by thrown food. A middle-school boy had mustered up the courage to talk to the girl of his dreams when suddenly a student in the cafeteria was taken down with a doughnut and there a huge food fight broke out, whereupon the boy's mission to save the girl from the school bully began.