This is my all time favorite Settlers trick. I had come into possession of a Monopoly card. This was late in a six person game when all the players had a ton of cards in their hands. When it was my turn, I noted that almost all the ore was handed out (by looking at the bank’s stack). I had a lot of it myself. So I traded heavily by giving away ore and getting other cards in return, with some haggling to not raise suspicions. Once I had traded all my ore away, I played my Monoploy card to get all of it back. I got a crazy number of cards and I can never forget the look of shock on my friend’s faces.