The Boyfriend by RL Stine

Monstrous teenagers and teenage monsters!  Thrill as mean teenagers fake deaths, fake zombiefication, fake other deaths, and then can't figure out why nobody likes them!  Chill as everybody has a silly expensive car but no moral compass whatsoever!  It's 2 AM, do your children know how to close and lock a window? Joanna is a stuck up bitch.  Her boyfriend Dex is an insane gaslighting.... secret prosthetic makeup expert?  When Dex falls off a cliff and dies, Joanna keeps seeing him around, like, at the mall.  Is Dex dead?  Is Dex alive?  Are all of these people awful humans anyway?  It's The Boyfriend by RL Stine!