Remember high school movies? They’re thin on the ground these days, meaning the kids might have to reach back to older teen films whose stars are now pushing 50. The ones made by John Hughes are weirdly undying. But far more respectable than “Sixteen Candles” and “The Breakfast Club” is the one dropped into that nice and peppy era. “Heathers,” with Winona Ryder and Christian Slater offing demonic popular girls and dumb jocks, was both a bomb, in that it tanked at the box office, and a ticking time bomb, in that it eventually destroyed an entire genre. Once it bloomed on home video, it created a generation of smart alecks, quick to deploy sarcasm and make jokes about cow-tipping. Yes, it birthed the likes of “Mean Girls,” but it’s always better to go back to the source.