Bowling Ball Swing
This is a game usually seen at traveling carnivals and funfairs. A game is set up where a bowling ball is suspended from the roof, a few centimetres from the floor. In front of the bowling ball is a pin (or a bottle). The aim of the game is to knock over the pin by swinging the bowling ball. Only catch, they must swing the ball around the pin, and hit it on the back swing. You must arc the ball, hitting it straight on, doesn't count.
This might seem like a fun game, but it actually can't be done. As the ball swings past to the left on the throw forward by a certain margin, it will also miss by the same margin on the right as it swings on the way back.
The con man may 'show' you how it is done, but in this case the pin has been placed off centre making the shot possible.
Usually not more than anything over £5 per person, but depends on the scammer and how addicted the mark becomes.
How to avoid being scammed
If you ever see a game like this, ask to see if it can actually be done. Then pay close attention to how the game is set up, there will be a sleight difference between your turn and the scammers. When it comes to your turn, ask the con artist to move the pin, as you think it wasn't quite the same. They won't want to play will you after that.