Last year I went to Paris and found it amusing watching the guys who do the street games where you bet money if you can pick one of the three objects that has a different color on the bottom. At first they give you a trial run, which makes it easy for you to win. But most of these guys are pretty good at fooling you when there is money on the line. I'm wondering if anybody here has the knowledge to help me create a simple hack for this, which would guarantee a win everytime. My idea would be to only win twice then move on to the next person on the next street or whatever. Need a chemical that I can apply to my fingers, then when I do the trial run, I touch the right object with the invisible chemical. Then I would need a pair of sunglasses with a special filter I wear, where only I would see the chemical marking. This hack wouldn't work if it was the cup and ball trick. But at least in Paris, the street guys (and their fake audience) always used the one item object, that just has a different color on the bottom. Who here has a way to do this? What product can I buy to make this work?