Clean Connection Blue by Marc Oberon

Effect:
You show two cards with their centers ripped out. Then very visibly you link the two together. The cards are then unlinked just as visibly and handed out for inspection, leaving nothing to find.

This can also be performed as an impromptu effect, tearing the cards in front of the spectator before you begin.

Excellent step by step instructions and illustrations.

The only props required are three cards (that you are happy to rip up!)