I don't usually comment, but after reading a bunch of these stories I feel compelled to share. I've got a couple of stories, both scary but not in a paranormal way. I'll try to be brief.
Story the first
This happened when I was a kid and can be explained by the fact that I was delirious with flu, but I struggle to remember another time in my life (with the exception of my second story) when I felt such primal terror.
I awoke one night, feverish and hallucinating, to find that the my bedroom (which was a pretty standard rectangle shape, but with a small "corridor" of about six feet that led to the door) around me was moving and twisting. The shape would change, things in the room would flit in and out of focus, and when I looked at the small corridor, it seemed to stretch before me and extend outwards infinitely, with the door barely visible at the end.
Thoroughly freaking out at this point, I got up out of bed, stumbled to the door and made my way into the hall. My other had obviously heard me and come to check on me as she was in the hall. Things only got worse from here on, as when she spoke I could see her lips move but I couldn't hear anything. I distinctly remember myself trying to speak to her to tell her I couldn't hear here, I was seeing things, I felt sick etc, but she kept "talking". After a moment or two, she turned and walked away, but it was wrong. The way she was walking was unnatural, like how a ghost or entity walks in a movie. Ever so slightly sped up as if someone had hit fast forward.
I recall making my way back to bed, heart pounding, and cocooning myself in my covers. I was told later that I wasn't making any sense, just gibbering, and didn't seem to be responsive when I was stumbling around in the hallway. The emotions I felt at the time still stick with me to this day.
Story the second
Up until I was 18 I lived in Hillsborough, Northern Ireland, which is about 10 - 15 miles from Belfast. If you're at all familiar with the UK / Ireland you'll know that NI was a particularly... heated place to be for most of the last century.
When I was a teenager I worked in a store in the village. At the end of a day during the summer, when I was still light outside, a colleague and I were cashing out the tills, doing the counts etc when suddenly there was a righteous blast from outside that shook the windows and knocked dust from the ceiling tiles. I swear I even felt the faint concussion of the blast. Abandoning what I was doing, I quickly made my way to the front of the store and looked out through the glass on the locked front door to discover that the street was silent, empty of people, covered in some sort of debris and clogged with dust.
At this point, now heart pounding, adrenaline pumping and thoroughly freaking out I unlocked the door, threw it open and stepped into the street.
To find that one of those gigantic crane / truck hybrids had been making it's way through the center of the town when one of its tires had spontaneously disintegrated, releasing it's pressure and shedding rubber debris all over the street.
Even though the cause wasn't a bomb, as my paranoia had led me to believe, it was still incredibly lucky that no one was harmed when the truck tire blew out.
TL/DR Flu hallucinations and terror attack paranoia are not a lot of fun.