10 Albums With Actual Hidden Messages
4. Electric Light Orchestra Appreciate Your Persistence

People often forget that ELO have such a peculiar history. They tend to remember that it was formed by Jeff Lynne the robot-voiced Mr Blue Sky but not that he was helped along the way by Roy Wood. As in, Roy Wood out of Wizzard. As in, Wizzard who did I Wish It Could Be Christmas Everyday. And now we've got that song stuck in your head four months too early, and for that, we apologise. Bad luck and all that. Wood went for the glittering camp pop dollar whilst Lynne soldiered on with the earnest bombastic rock, but Electric Light Orchestra boasted a pretty good sense of humour too as evidenced by their hidden messages.
https://www.youtube.com/watch?v=9-3PS5sdv3c
ELO were one of the bands accused of featuring Satanic commands within their tracks; especially with 1974's Eldorado, something which they poked fun of with a couple of nonsense backmasking snippets on the follow-up record Face The Music. Deciding that wasn't enough, though, they then recorded an album that was actually called Secret Message, and was stuffed to the gills with them: puzzles in the lyric book, stuff concealed with the record sleeve itself, and a good half-dozen reversed messages in the songs (including "Thank you for listening"). They also wanted to slap a satirical sticker on the cover, warning impressionable teens that the album contained subliminal messages, which got nixed by the record label. Spoil sports.