A subliminal message is communicated below the conscious level of perception.
By nature, you will not be aware of receiving one.
This site can help you out.
Subliminal messages can be embedded in any picture, video, or noise. You could be receiving one at this very moment. These sections contain information on subliminal messages themselves, their history, the legal issues surrounding them, and how they are implemented into music and audio.
© 1999 Matt Feusner and Brad Griffith