Here is the presentation: "I am going to find your card, if I do not find it, I'll give you cash. Worth 50.000 Euros. No kidding. I never messed up that trick. And I never will. You know why? Because I am that good." After that speech you better deliver. And of course you fail.
But instead of giving them 50.000 Euros you give them shredded Euros. They are cheap. In fact I have about a million Euros right here. And I got them for free.
It is a useless but nice souvenir.
PS. It would be wise to use the currency of your country.