[WhiteKnight]

When I was in Berlin, I observed what is commonly known as a "shell game." There was a guy with a mat, three "shells," and a small ball of some sort. The "dealer" would put the ball under one of the shells and shuffle them around using some sleight of hand. People would then be given the option to wager a fifty euro note on which shell the ball was under.

I watched this for half an hour or so, maybe 50 trials. Every single time I was able to correctly determine which shell had the ball. (Un?)fortunately I was young at the time and didn't have sufficient money to take a shot. I'm going to go out on a limb and assume this guy isn't charitably giving away his money, but the game didn't seem very hard to beat. People seemed to lose with surprising frequency, I think some of them might have been inside men. At one point the dealer even offered to give me a shot after someone had guessed unsuccessfully... why would he be offering a neutral EV bet?

So what's the gig? Anybody else familiar with what I'm talking about and how this guy hustles money? Some sleight of hand after the victim picks perhaps?