Take one tissue and poke it into a tent and tear the tip off. Place the tent into your hand so no one can see it. Then take the regular tissue and hold it with both hands.
Show the tissue on both sides, then poke it into the hand that has the secret tissue. Grab both ends of the tissue and hold them between your finger and thumb so it looks like one piece. Then tear away at the hidden tip and when you open your hand, you will reveal the tissue is whole again.