One memory that happened to swim back into my consciousness earlier today kinda fits the bill here.
A few years back, I was renting an older turn-of the century two-up-two-down terraced house in South Belfast. Very much a Victorian city dwelling, with an outshot kitchen opening into a small paved yard, and a disused outside toilet occupying the space between the back of the kitchen and the wall to the alleyway behind.
The yard was horribly overgrown with weeds, and the outside toilet was packed full to the corrugated steel roof with musty old cardboard boxes. Over the next few months, I tidied up the yard as well as the house, and got round to clearing out the boxes from the toilet area. It turned out that the toilet pan and cistern were long gone, and the sewage outlet plugged with cement, but I thought it would make a good enough place to store my bike and other outdoor stuff.
The walls on the inside were whitewashed roughcast plaster, and I had the bright idea of putting in a nail so I could hang up the yard brush. But, on only a few taps with the hammer, a large chunk of plaster broke off, to reveal the brickwork behind. And... there was something else behind there, too. Then I realised that all the plaster seemed a bit hollow, when I rapped at it with my knuckle... and some more bits fell off - and then, with an icy chill I realised what had been revealed in all its abject horror...
See, the thing is that no-one gets this, no-one at all. Everyone I've ever spoken to about the episode looks at me like I'm very weird for finding this in any way scary, and yet it still creeps me out more than pretty much anything else that's ever happened to me. But here goes.
There was a buddleia tree growing on the roof of the outside toilet, way back where it joined onto the wall with the yard of the neighbouring house. That was fine, there's a lot of buddleia in the area that self-seeds everywhere, and often grows from cracks in walls. I couldn't get up there to remove it with the rest of the weeds, and hey, the butterflies like it.
But this one, this buddleia, had grown roots right down from the roof to the ground, between the brick walls and the plaster. On both sides.
Thick, cable-like roots, over seven feet long, had forced themselves between the brick and the plaster, and on down into the ground. And I was now standing inside the structure this freaky tree had created. The tree was outside of me. I was inside of the tree's sphere of influence. It was all around me. I was consumed. It felt like something out of an HR Giger painting.
It's no good, I can't convey the horror that this realisation still instils in me. All I can say is it really, really freaked me out to the point that I never went back in there again. Even twelve or so years later, it still bothers me a lot. I had a conversation about it this morning, which has brought it all back, and then some.
So yeah. My ultimate non-scary thing that's scary is a tree on a roof.