Krayzee
i think baby one more time.
"Sleep with me, I'm not too young" That's the message.
Nirvana's Smells Like Teen Spirit- if you play the ending, when he's saying "A Denial" backwards, you can hear him say "I hate you."
Another One Bites the Dust by Queen- He says "It's fun to smoke Marijuana"
Fire by Night by ELO- They say "The Music is reversable but time is not. Turn Back, turn back, turn back...
Also, in a couple Pink Floyd songs. In one he says something along the lines of. "You have found the secret message. Send your responses to Old Pink at the farm." In another, he says "I buried the Parakeet in the backyard. Why are you playing the record backwards? You're going to break your needle."
ELO's and Pink Floyd's were done on purpose, but it's still a hidden message.