Ron Frost's XTRA- XTRAORDINARY
Several assorted cards are shown on both sides and one card is chosen.
A person imagines that there is an "X" on the back of the chosen
card's back. The cards are spred out and an "X" is now on the
back of the chosen card.
The big surprise comes when all of the non selected cards are turned face-up
again they all have a large "X" across their faces! All is left
for "X" amination.