Double Taps
Double tap is a rule that can be called by the server in a four square game before the game begins. It allows players to hit the ball twice before having to hit it to an opponent's square. This allows for misdirection from players, keeping everyone on their toes, and also allows players to block incredibly hard shots from other players and still have a chance to hit it back into another square. This rule changes the style of play in four square and allows for more slams and strategy, but is not part of standard four square rules.
Body Language
In standard four square, players are only allowed to hit the ball with their hands. With the rule of body language, players are allowed to hit balls to other squares with any part of their body, such as arms, legs, feet and even heads. This rule allows for exciting plays and returns from players who are quick to the ball with all parts of their bodies.
Black Jack
Black Jack is a rule in four square which really puts hand eye coordination to the test, by allowing players to catch balls hit in the air to them from other players. When the ball is caught in the air, the person who hit it is out. However, this is a bit of a gamble for whoever is trying to catch the ball; if he fails to catch it, he will not be able to return it because he has already touched the ball once.