Windows
These holes from which one can see the outside world in all of it's chaos are truly horrifying to have around. Not only that, but anyone can look inside your home from the outside! All sense of privacy gone, all sense of security, all sense of normalcy!
What if you were sitting in a room, drinking tea, when you happened to look up and see a grotesque face staring at you from the window. Blood oozing from the eyes and grey skin wrinkled like paper. You scream and enter such a state of panic that it causes a heart attack!
What if you were outside, going for a walk with your child, when you happened to glance into a house and see a group of people holding hands and performing a seance? The image of the white clad folks, with strangely eager faces would scar your child forever.