You display three large colored cards....red, yellow, and green.  You place the cards into the fold of newspaper or into an envelope. You now openly remove the red and green card, and explain that the yellow card is gone.

The spectators are not impressed and think that the last card is still in the envelope. But when the card is removed it says "Wrong"!  Perhaps the yellow is simply printed on the other side?  Turn it over it and it reads "Wrong Again"!

The newspaper or envelope can be shown freely...the yellow card really is gone!