The objective of a suggestibility exercise is for stage hypnotist to quickly find out who is suggestible or willing to listen and follow the instruction. This is crucial because if it is not done properly, it can spell a failure for the hypnotist.
Actually it is not difficult to come up with such a test. One way is to find someone who knows how to snap fingers (and most people knew). Give instructions that he can put his thumb to index finger or to middle finger. When you say snap the finger, he shall do so. After a few times, stop for a while and then resume the same instruction, only this time asks him not to make any sound when snapping the finger.
After that, alternates your command for the snapped finger to produce sound and not to produce sound.
It is simple, isn’t it?
But you will be surprised that not everyone could follow such simple exercise.