jasonharper writes –

This hack will allow user-written software to be run on a JuiceBox media player toy. It works by tricking the built-in picture viewer application to run code contained in a .JBP picture file that starts with a specific 8-byte sequence. Normal operation of the JuiceBox is not affected, other than the 1-out-of-18-quintillion chance of a real picture containing the trigger sequence.

instructables : Pixecutor – run software on a Mattel JuiceBox – Link & you can now get a pre-programmed chip from the Maker – Link.