Most fans of Dragon Ball Z are aware of the ending theme song of the original TV anime, but it's news to most that towards the end of the song is a secret message that can only be heard by playing it backwards.

"Detekoi Tobikiri Zenkai Power!” performed by MANNA, was the ending song for the first 194 episodes of the TV series that premiered in 1989. At the beginning and end of the song are some gobbled up sounds, which, upon listening, just seem to be a part of the quirky theme.

But when played backwards...that is when the secret message can be heard! Created by first reading out names into a tape, playing it backwards, shifting the pitch, then overlaying the names onto the track, the message names off all those who worked on producing the song, ending with a "gambattan dayo!" Ganbattan dayo is translated into "worked really hard!" or "did their best!" So the secret message is to the workers in the studio and a recognition of their efforts and the hard work they put into making "Detekoi Tobikiri Zenkai Power!” 

See Song Ha Yoon and Teen Top’s Changjo in the lighthearted fantasy comedy Sweden Laundry:

The Beatles were the first ones to be known for recording messages backwards, or backmasking, and including them in their songs. Since then, many bands, including Pink Floyd, Slayer, Marilyn Manson, and even Prince, have done the same. And now included in the list of backmasking bands is MANNA.