I'm like Aur. Believing makes things more exciting. That being said, I don't actually believe in ghosts or spirits or karma or heaven or hell or any of the standard superstition stuff.
No, mine are a lot more fun *sarcasm*. I sometimes experience split-second and absolutely ridiculous inventions of fancy, or short-term delusions. Once I was washing dishes and Joe entered the room behind me and I was convinced that he was a human-sized locust or grasshopper due to the noise of his keys scratching together, and I turned towards him with a large knife (remember that??).... And once after a rough break up I was convinced that people who saw images of me would get smallpox because I was infectious/contagious/dirty/etc, since the break-up was about whether I'd lied about having herpes when I failed to mention that I get a cold sore about once a year. I put on gloves and clothes I could discard after and set to removing images and suspending/deleting accounts so people wouldn't get sick from looking at me. That specific folly lasted about 10 hours.
Scratch that. Most of them aren't fun.
Every so often I'll have waking dreams -- like, at night, when I'm mostly awake, but still imagining things very vividly -- of someone (or the wrong someone) being in my bed. Or I'll be blind, and search for a light switch in a panic, usually on the wrong wall, with my eyes closed. Once or twice I've imagined blood or another liquid leaking down the walls or from the ceiling.
I don't believe that these are real or mean anything, but they're certainly an interesting quirk of my brain.