To be fair, I've observed screaming of this sort on about a third of all subway cars I've been on.
It's late. You're tired. You just want to go home, kick back with a cold glass of Caipirinha and maybe watch a little futebol. Unfortunately, you live in Brazil, which means that you're constantly getting effed with by Programa Silvio Santos and its team of people who go to great lengths to keep you in a state of constant anxiety.
So, even if you get off one train haunted by a spooky little girl ghost, you're bound to step onto one that's being attacked by a herd of ravenous zombies:
You're probably better off just taking the bus.
On second thought...