As long as I can remember, I've felt an urge to lock the car door and not press too much against it when the car's going around a curve, because the idea of the door swinging open and me falling out of the car while it was in motion seemed scary. It's not that this is an obsessive fear: I don't sit up thinking about it, I don't spend car rides with my teeth chattering. It's a very low-level thing, but it's curiously persistent. I've been doing this since childhood and it pops into my mind every single time I'm in a car, though only for the second or two it takes to lock the door, and then it's passed. (Unless I stop to think about why this happens, as I'm doing in this post.)
I don't know where this comes from. It's not like I knew someone to whom that happened, or even that I saw it happen in a movie and it made an impression on me. I have no particular origin for it. I suppose once I thought about it and thought "that would be bad" and then for some reason I can't identify it stuck. And has stuck through thousands of iterations, without ever getting bigger and turning into a real fear, but without ever going away either.
To a lesser extent I sometimes get the same reaction to the idea of having my arm sticking out of the car window, the threat of the car coming too close to something (a mailbox, another car, etc.) and catching my arm. I reassure myself that before it hit my arm it'd hit the side-view mirror and in all the years of being in cars, I've never seen a rear-view mirror get clipped by something in traffic. So I can still keep my arm out the window on a nice day. But the idea always pops in briefly.
Another thing like this is (stop reading if you don't want to be exposed to something gruesome) the idea of puncturing my eye accidentally with something sharp. Again, it's not like I sit around dwelling on it, or refuse to pick up scissors. This isn't some morality play movie about phobias or supernatural "everything means something" obsessions. The idea doesn't hold me very firmly but it also never fades. And again I have no idea why I have this idea at all. I don't remember ever hearing of anyone having this happen, or having such a thing make an impression.
(Closest thing I can think of is, as a very young child, I was in the car while my parents went to see The Godfather at a drive-in. I was more interested in the moon, which was red that night, than in the movie, which was completely uninteresting to a five-year-old. But a scene in which someone got shot in the eye through glasses made an impression. Still, I never wore glasses and never was around guns, and the 'fear' is more associated with humdrum things like paper clips and accidents than with anything as violent as that murder.)
Even trying to explain this, I feel like people will misinterpret this as being about obsessions. There's a sense that any worrying image that haunts you must be extended both in time and intensity; I don't know a word for something that's persistent like this, but not intense. So if I ask, do you have anything like this? I wonder if people will come back with actual obsessions or phobias.