Something spooky is coming to The Sims 4 tomorrow

EA is teasing something spooky coming to The Sims 4 tomorrow, presumably in celebration of Halloween. 

Though the developer hasn't fully revealed what it'll be, they've posted a number of teasers on The Sims Twitter account, including a photo of a woman scared of the grim reaper and another of a man who wet his pants as something terrifying approaches. A third image was posted of a gnome swinging on a rope with a message from EA that reads: "It's going to be an exciting week in [The Sims 4]."

So what can these unexpected guests be? Ghosts? Ghouls? Vampires? More importantly, will this be a free content update?