Whisker From Cerberus
How To Get It
To obtain this item you must first go to Apollo's temple and get a reed pipe. Then talk to the muse with the pipe and she will challenge you to a memory game. Beat this game and she will give you a magic tune. Go to the underworld and play the tune on your reed pipe in front of Cerberus. He will fall asleep and you can take the whisker.
The Secret Message it comes with is "objects will rule".