Flexibility: "The ability of the players to change the currency of the game (that is, the tools they use to play it). 'Some games...can be played properly with only one kind of currency, while others, such as exhibitionistic games, are more flexible",[11] so that players may shift from words, to money, to parts of the body. Tenacity: "Some people give up their games easily, others are more persistent", referring to the way people stick to their games and their resistance to breaking with them.