Lots of horror movies seek a cheap thrill by having children say or do something which is completely innocuous, but in the context of the movie it is scary. I say this as though I have watched a lot of horror films, which is not true. I am scared of my shadow when it comes to movies (I was scared of Scream 2...yes, I know it was a parody) and I have not really ever watched horror movies. But the television commercials often show innocent children who are scary because they are doing innocent things in a frightening context.
(As an aside, it once concerned me that these kids were in these movies and possibly suffering psychological harm because of their roles. I now understand that the kids usually just film their specific, quite innocent scenes and never see the entire film or understand the context of the film. So I am no longer particularly concerned.)
Anyways, back to kids doing innocent things which seem creepy because of the context. My son does something that is entirely innocent but scares the socks off of me. Here is a contextual description:
It is usually late at night and I am fast asleep in my bed. I wake up and there is someone standing over me and it is terrifying.
What has happened is that my son has walked into my room to ask me something - typically to ask whether he can get up and play with his toys yet (the answer is always "no" because it is the middle of the night). He has walked silently into my room and stood next to my bed to wait for me to wake up. This is all exactly what he is supposed to do, as we have asked him not to bellow for us from his bed because he wakes up his brother. Nonetheless it is incredibly creepy. When I am waking from my deep sleep it is hard to put the person into context and it always makes me jump.
Another creepy illusion used to happen in our old house with mirrors. I would normally say that I don't believe in ghosts, but that cannot be true given what I am about to explain. If a person has no belief that ghosts exist whatsoever, that person should never be afraid of an illusion that looks ghostly, right? And I have been scared by this one a few times: It is very simple, you walk into a dark room in a place you are somewhat unfamiliar with and you see yourself in the mirror, in the dark. Because you don't know that there is a mirror in that spot, you jump because you think it is a ghost. This is silly, right? But it happened to me a handful of times when we moved to our new place in Calgary and I was not familiar with the locations of all of the mirrors.