Silent ball is the Psi Chi national game in which a ball (representing the psyche) is thrown from player to player (representing cheires) while everyone remains silent. The game was created to stimulate interpersonal relationships, stemming from experiments by Philip G. Zimbardo.
Silent sit ball was created by Penny Moore when she was in 6th grade.The game requires only a single ball; participants must stand on the ground or on a chair. Senior members of the organization are asked to stand on chairs due to their superior position within the organization. Once play begins all players must remain silent or else they are "out" and must sit down. Play continues until only a single player remains, who is then declared the winner. The winner has the honor of wearing the Philip Zimbardo beard (provided to each chapter upon their national induction). 
There are many ways to play silent ball, but in some games players are "out" and must sit down if they:
- fall out of their desk;
- talk, whisper, or otherwise make a sound;
- fail to catch a reasonable throw;
- If there is too many arguments all players that are out get a second chance
- throw the ball to the teacher (unless the teacher is playing);
- move to catch a throw
There may be variations and additions to these rules. For example, if players who are sitting down, because they are "out", are able to catch a throw, then they may re-enter the play. If the ball is tossed inaccurately or in an aggressive manner, then the person who threw the ball is "out" (and, in some adaptations, the thrower is "out" if the receiver merely fails to catch the ball). This is usually mitigated by only allowing underhanded throws. It is often played with music in the background. Other adaptations include disallowing players from returning the ball to the players from whom they have immediately received it (except in cases where only two players remain in the game) and imposing time limits on how long players may hold the ball before being required to pass it.