Mind games are one of the most interesting and portable types of games you can play. Many of them can be played anywhere at any time; no preparation or props are required. If you're standing in line or stuck in a long car ride, mind games can be a way to entertain your friends as well as impress them.
Mind Games With a Partner
Some of the most impressive mind games cannot be done alone; you need a friend who's in the know to play along with you. The two of you can surprise the rest of your friends with your apparent ability to read each others minds. To play these games, you must first teach them to your partner. An example of this type of game is Black Magic. In Black Magic, your partner goes out of earshot while the rest of the players pick an object to be "it," which can be anything in the room or nearby area. Your partner then returns, and you ask her whether different objects are "it." Just before you ask about the object that is "it," you should ask about an object that is black. Your partner knows that the object you pick after the black object is the answer.
Mind Games Without Partners
There are many similar mind games that allow you to stump everyone present without a partner. For these, all you need is to know the secret of the game. Depending on how long you want the game to continue, you can make it more or less difficult by your body language and other actions. For example, in Counting Sticks you tell the group that you will indicate a number between zero and 10 by your actions. You then place sticks (or forks, or any object that's available) on the ground. After setting down the sticks, you put your fingers on the ground near the sticks. The number of fingers that are touching the ground is the number you are indicating. You can make this game more difficult by carefully placing the sticks in an intricate and complicated manner and then indicating your fingers very casually, as if by chance. This will encourage the players to focus on the sticks instead of your hands. If you want to make it easier, you can lay the sticks more haphazardly and place your fingers more exaggeratedly and deliberately.
Riddles are another mind game that you can play anywhere and that don't require anyone else to be in the know. In order to stump your friends with riddles, you have to have the riddles memorized. You should be careful to remember the important details of the riddle and its answer, but you can always feel free to make up more details if you want to. Usually, the more details you include, the more difficult the riddle will be for players to figure out, since they won't know which details are important for the riddle. Examples of riddles are listed at increasebrainpower.com.