Disney characters signing pillow cases??

I read somewhere that if you brought two pillowcases and waterproof markers, that sometime during the cruise, it would be signed by the characters..

What kind of Markers? who should you give the pillow cases to??

Thank you...leaving Sunday on the DREAM with my granddaughter.

See this thread

http://boards.cruisecritic.com/showthread.php?t=2115413

I brought a mat that would go around a photo. I also supplied all of the markers. We were very happy with the result!