Elephant.

Two teenagers (males) living in Oregon who fuck eachother in the shower, decide to go on a school shooting for fun. They order military rifles from some website, have a fucking FedEx guy deliver the guns to them. The "big day" comes, so they eat pancakes for breakfast then have a morning session of "oooh whats that in my ass?" in the shower. They march into school, and just start shooting people. Nobody calls the police, and they even fucking toss some grenades around. Then, one of the teenagers shoots his gay butt buddy for no reason at all. Yep, shot his best friend for kicks. The movie ends with another couple hiding in the freezer in the cafeteria, the shooter finds them and goes "Iny-Miny-Minie-Mo, Catch-the-tiger-by-the-toe" to decide who he's gunna shoot first. Then the movie ends. RIGHT FUCKING THERE.