I'm always curious about stuff like this so I don't mean to be rude, but in all seriousness, how do you think a shower head will hurt you? I understand it isn't rational so maybe the answer is "I dunno" but figured I would ask.
I suspect it is a sensory-processing thing. I'm reading waaaayyyy too much into this, but people on the Asperger's syndrome spectrum--even slightly--and more likely to be in the HN commenter crowd--have peculiar sensory issues. Often you see it with things like aversion (or preference) for certain food textures, so it doesn't seem out of left field to hear that anticipatory auditory and sensory stimulus (like the death rattle of a showerhead, or the subsequent burst of lukewarm water) would be a trigger. And that it would be passed down genetically or by behavioral role models...
part of the struggles we're having with my autistic son center around toilet training -- I think in large part because the bathroom is full of things that make running-water type noises, and those freak him out.
My experience is this, As got in to mechanical work (lathe, milling etc) and computer. Before about 16 i thought everyone will do right thing only and not really cheat absolutley but the real work hit me and i found people will do mediocre job for no reason or simply lazy so when ever i see structure or car i double check break or think it may fall...
The closest thing I can think of is maybe a bunch of vines will come out and grab me or something.
don't worry, you are too big to fit through the holes, so worst case they will just immobilize you until you yell enough that someone comes and kills the vine monster. they might see you naked but you won't die. :D