Slaughterhouse High by Robert Devereaux

It's prom night in the Demented States of America. A place where schools are built with secret passageways, rebellious teens get zippers installed in their mouths and genitals, and once a year, on that special night, one couple is slaughtered and bits of their bodies are kept as souvenirs. But something's gone terribly wrong at Corundum High, where the secret killer is claiming a far higher body count than usual . . . Slaughterhouse High is Robert Devereaux's slicing satire of sex, death, and public education.