Heathers was a dark high school comedy about Winona Ryder's Veronica befriending cool outsider Christian Slater's J.D., only to realize that he is in fact a homicidal lunatic. Slater plays a new student who wears a trench coat and sits in the corner. Two jocks in letter jackets immediately decide to bully him as part of the ongoing Coat Wars, and Slater responds by pulling out a goddamn gun and firing blanks in their faces.
New World Pictures
Add a fade to black and a government seal, and this is an anti-gun PSA today.
In the next scene, one of the titular Heathers scoffs at the thought of J.D. getting any punishment worse than a brief suspension, and Veronica finds his antics both hilarious and kinda hot. And indeed, J.D. is allowed to return to school without any consequences, which makes it pretty easy for him to murder three students before attempting to blow the whole place up and finally committing suicide via bomb vest. You can probably see why this film didn't age well as a comedy, but aged fantastically as a grim portent of the dark future to come.