The Evil Decoder (Ouiji Subwoofer) is:

A modified subwoofer which vibrates a Ouiji Pointer over Ouiji letters, spelling out the sinister directives that have been encoded in all popular music as subliminal messages. produced for the Playlist Thursday dj set of the same name, July 27, 2006 at the Power Plant Contemporary Art Gallery, Toronto.

I love projects that use the simple physical properties of objects to give themselves personality. – [via] Link.