Radio Static
As a kid, I was playing around with a radio once, just slowly spanning through the static trying to find a station. I had found an old television antenna, attached it to the side of our house, and ran a wire out my window to it with an alligator clip attached to the radio antenna, allowing me to get a way broader range of signals.
So I’m sitting there, middle of the night, slowly sweeping frequencies, and suddenly I get to this station that’s playing this very weird crackling sound. It sounded sort of like cracking knuckles, or maybe Rice Krispies cereal, but with a fixed, rhythmic pattern instead of being random. I sat there listening to it for a second. Then it suddenly stopped and I heard something bone-chilling. This faint voice said: “It doesn’t work. We’re already gone. We’re already gone.”
It took a second for the weight of the words to hit me, but when they did I freaked the heck out and almost threw the radio across the room. I’m pretty sure it was just someone messing around with a radio transmitter, but it sure scared the heck out of me at the time.