The joke is:
None of the teens in Heathers really commit suicide.
The protagonists kill their enemies and stage the crimes to look like suicides, because (as they’ve learned at school and from the culture at large) killing yourself is this week’s “cool” thing to do, which means the authorities won’t investigate any further.
Then these beautiful alpha dead kids are glowingly eulogized, so sure enough, bullied, beta kids start attempting suicide, too — and are duly mocked for “trying to be popular.”
Get it? If Heathers is still relevant, it’s because victims are the new heroes.