We've all see the 'Yvan eht Nioj' episode of The Simpsons, but hiding subliminal messages in music is actually a thing. 'Backmasking' was first popularised by The Beatles in the '60s, but it was used by magicians as early as the 1900s.
It's not always a Satan thing of course, some bands like to send secret messages to fans, make fun of the idea of evil subliminal messages, or to allow them to swear without getting censored.
But other times, bands like using it to scare everyone. Thanks for giving me nightmares Slayer.
Here is the Lifelounge guide to subliminal messages:
Britney Spears
Message: Apparently "...One More Time" says "Sleep with me, I'm not to young" backwards.
Beyonce
Message: "Single Ladies" is actually about Satan and the Illuminati. So there you go.
The Beatles
Message: One of the many backmasked messages The Beatles used (and the creepiest) was playing the mumbling at the end of "I'm So Tired" backwards and getting "Paul is a dead man, miss him, miss him, miss him". YIKES.
Rihanna
Message: That Rihanna has sold her soul to the devil. Oh, and the Illuminati.
Franz Ferdinand
Message: The mumbly bit before the second verse is "She's worried about you, call your mother", because they wanted to do the opposite of a Satanic message. Cute.
Lady Gaga
Message: She worships Satan! Or Freemasons!
Bruno Mars
Message: Unlike his showbiz buds, Bruno is ant-Illuminati and ant-Satan. And anti-good music, HEYY-YOOO!
Pink Floyd
Message: That you've discovered the secret message, funny bastards. (Also, the funny farm bit may refer to one of them being in a mental institution).
Katy Perry
Message: I just don't know that Satan would choose Katy Perry to send his message.
LMFAO
Message: "THIS IS A LOT OF GIRL ON GIRL KISSING THROUGHOUT THIS WHOLE VIDEO... BECAUSE OF SATAN".
Prince
Message: That the Lord is coming soon. Cool. Kinda creepy that he did that on purpose.