There was a paper card listed in the slot guide from the Circus Circus Reno that was a playing card design with 8's in the corners and said "It's Your Lucky Day!" issued back in Sept 2003. A similar card with Aces in the corners was just found that was issued in Dec 2003.

A scan of the new card is on the ChipGuide now
http://themogh.org/cgupdate/cg_showpic.php?pic=../cg_pix/nv/122146a.jpg&picr=../cg_pix/nv/122146.jpg