cool hidden message.

Ok, here's one: On his single 'Windowlicker', Aphex Twin hides an image of his own face on the second track 'Formula / Symbol'.

Here's a quote from wikipedia-

'Viewing a spectrogram of the second track reveals hidden images that were apparently synthesized as sound by Aphex Twin for the express purpose of being discovered in this manner. It is one of the few instances of an artist using steganography to embed a representation of his own face into his music (see also these artists: Interlace - Innuendo, Venetian Snares - Songs about my cats). A spectrogram of the first track, "Windowlicker", also reveals a spiral at the end of the song. This spiral is more impressive when viewed with an X-Y scatter graph, X and Y being the amplitudes of the L and R channels, which shows expanding and contracting concentric circles and spirals.

https://en.wikipedia.org/wiki/Windowlicker