Sextronsity is the latest in the Asian horror genre. At a girls' school two chicks are smoking opium in the bathroom with some a black market manga so reprehensible in content that both of the girls go insane and instantly embark on a killing spree.
Many corpses later, they are shot by police and become malicious ghosts that inhabit the school cafeteria, seeking revenge by pissing on the kimchi just before the lunch bell. Needless to say, this sends the administrators into an downward spiral of sex and death, and before you can say "There's a girl with dark hair crawling out of a well" there are several more dead bodies including one girl who's mistakenly stir fried and served as 'breakfast squid'.
Subsequently, a bipolar homicide detective from Hong Kong appears. Then she falls down the well and is never seen again. No one seems to wonder why. Finally the manga is burned and the curse is lifted although by this time most of the students are dead and some of the parents are beginning to wonder if they should ask for a refund. (In a sequel currently in production, the curse lives on in the refund checks.)