One of the freakiest thing that's ever happened to me...
Summer of 1990, IIRC. I had made a tape of John Lennon songs, Beatles-era stuff, recorded directly from vinyl to cassette.
I went to bed at night a popped it in and I was soon off in a semi-conscious state. The last song was All You Need is Love, and as it started fading out, out of nowhere this very loud voice came out, masking the music. I woke up w/ my heart pounding in my chest wondering where that came from. Stopped the tape. Hit rewind. There it was again!
I could never figure out what it was. It was a new tape and I'd never heard such interference in recordings before, nor did I ever hear anything similar after. I kept that tape for years, to a point where I totally got used to the interference during the fade out and it's almost as if something's missing when I hear the unaffected recording...
As for what it was saying, I couldn't figure that out either. Sounded like "Ay Ta Tay Ta Taw (short pause) Ta Taw!!!"
I've never been inclined to rely on supernatural explanations - I'm sure there is a 100% rational explanation - CB Radio interference or whatever. So I never really bothered w/ it. But that first time I heard it was certainly intense.