How do you make someone faint with a pressure point with no pain?

You either hit the point with the appropriate amount of force. Knowing where the pressure points are and how to attack them is something only taught to experienced martial artists. Without the appropriate knowledge, it is very easy to hurt someone very badly with results that neither party will be happy about.
hit them on the base of the neck on both sides or bite them in the back of the neck hard for 10 seconds