Ghosts? Ghosts.
I absolutely hate the idea that ghosts might exist. There's zero concrete proof that ghosts exist, and I've yet to experience anything 'super natural' in my lifetime to warrant belief.
Every single ghost story can be explained. Sometimes the explanations are theory, but it still has more weight than 'dead people messing with the living, with zero rationality in their actions' as far as I'm concerned. I'll give you an example:
A friend of my mother's was dumbfounded when they found out I don't believe in ghosts (oh gee, it must be stupid to think clearly about something for more than ten minutes) and immediately began to spout story after nonsensical story to somehow 'make me' believe, at least that's my assumption because she certainly wasn't doing it for the sake of an interesting story. The first story was 'her dead father holding her shoulder a week after he passed away'.
Think about that for a damn second people. First of all, she said this happened at around 3 in the morning, meaning she was probably sleep deprived since she goes to work at 8 AM every day. On top of that, her emotional state was probably in disarray with only a week of grieving (this is taking into account the type of person she is, some people aren't affected for weeks at a time). Now, somebody who desperately wants to see their dead father again, in complete disarray, might actually hallucinate something like a sensation on their shoulder and the image of their father's face for a moment. Looking back on the occurrence, one might exaggerate after something like this happens.
Before someone spouts 'GHOST' they should think about the situation for a little while. Unfortunately not a lot of people do this. Don't get me wrong, it's fine to believe in ghosts if you really want to, just like it's fine to believe in god. I however, find it absurd.