I recently saw a demonstration where a blindfolded swordsman used a katana (large Japanese sword) was used to slice a large watermelon in half while it was sitting on the stomach of a live human being (who happened to be my friend). Don't worry, he's fine.

And I thought to myself what a wonderful thing to add to a magic act (so much more macho than a balloon animal)

So you get your spectator/assistant/volunteer/victim on stage, have him (naturally, he'll have to take his shirt off to prove that there's no armour or anything) select a card, sign it, return it to the deck then place the deck in the box

You then start your dramatic buildup as you put him on a table, put the card box on his stomach, put a melon on top of the card box, blindfold yourself, take your sword and slice clean through the melon, leaving the assistant and the card box unharmed.

For your magical climax, you can have any of the following
-Signed card found in one of the melon halves
-the card box opened and all the cards are unharmed except for the signed card which has been sliced clean in two
-the card box is opened and all of the cards are cut in two except for the signed selection


Cheers
James

P.S. If anyone actually tries this, I'd really appreciate a ticket to the show.