I'm wondering if "geometric nightmares" is a reoccurring dream I've had since I was a kid too, basically two cog-wheels linked with each other, but one is extremely huge and the other unbelievable tiny. I'd never describe this as a "geometric nightmares" though, but it does kind of sound similar.
Maybe there is something about "contrasts" as they all seem to be vaguely related to "big difference" basically.