Group starts in circle, one of the players points to another player to one side of them and says ‘zip’. That player turns to the next player in the circle, points to them and says ‘zip’. Thus the ‘zip’ is passed around the circle in one direction. At any time any player can say ‘zap’ to the person pointing at them.
When they do the player that says ‘zip’ must change the direction of the pointing. This means that they must react quickly by passing the zip to the person that just pointed at them. Now the ‘zip’ is passed around the circle, changing direction every time there is a ‘zap’ and vice versa. Lastly the person that receives the ‘zip’ or ‘zap’ may elect to yell ‘boing’ and point at someone anywhere in the circle. That player then restarts the ‘zip’ going in the direction of their choice. The group must really pay attention for this to work.