I thought of one, finally:
I have genuinely been trying to think of something I own which is genuinely unsettling and weird.
I remember I found a tape in a rehearsal space that I played on a broken walkman on the way home that sounded like the most horrifying monstrosity of mess. Turns out the tape was playing at half-speed on near-dead batteries, and played in a proper tape player you could hear why it was left behind. It was guff. Real, real shame though. It's disappeared to the great tape home in the sky now.