Backward messages in music (commonly known as Backward Masking) have been a controversy ever since the late 60s, when messages were found backwards on some Beatles’ albums that hinted Paul McCartney had died. The controversy raged extensively in the late 70s and early 80s when religious fundamentalists claimed that Satan possessed the minds of singers, causing them to insert messages backwards into albums. As we now know, many of these backward messages were in fact examples of Reverse Speech in music.
Just visit Reverse Speech – Music Reversals to listen the spooky samples yourself.