10 Albums With Actual Hidden Messages
Less "Hail Satan!", more "Call your mother, she's worried!"

In terms of hysterical moral panics over pretty prosaic pop culture, the Satanic subliminal messages in rock music scare ranks somewhere between all the people burning Beatles records after John Lennon's ill-advised Jesus crack and the time a large portion of the American population genuinely believed that playing Dungeons & Dragons would turn kids into occult-obsessed serial killers (mainly it just made them spend a lot of money on dice and get good at maths). And yet somehow it lead to congressional hearings, court cases, and an attempted bill to stop the practice of backmasking in music.
Backmasking is exactly what it sounds like recording some vocals and reversing them, then concealing them within a regular song. Starting with the rise of the Christian right in the late seventies and reaching fever pitch in the following decade, people with way too much time on their hands decided that Queen's Another One Bites The Dust had a secret message telling kids to smoke marijuana, or Stairway To Heaven by Led Zeppelin had a paean to the devil hidden amongst all the hippie stuff. Never mind that it takes a lot of effort to listen to a record in reverse, groups began to claim that backmasked messages could bypass the conscious mind and reach the subconscious, where they would be unknowingly accepted by the listener.
Obviously bands weren't actually brainwashing people and, as Judas Priest said when they were accused of inspiring a couple of people to kill themselves with a subliminal message in their song, they would prefer to insert the command Buy more of our records. but the popularisation of the concept actually ended up inspiring bands to start putting real hidden messages into their music. Thanks to those crazy religious types we've since had bands taking the backmasking thing and running with it, doing some even weirder stuff with the technique, and finding new ways to conceal extra stuff in their songs. Some are creepy, some are funny, some cause a bunch of head scratching here are ten of those albums with actual hidden messages.