Some people like the pet play aspect of it. Personally I like the idea of having your mind turned into a silly plaything. Becoming a chicken at the snap of your friend's figures is just a classic example. Bonus points if you heckle the hypnotist just to get placed into a deep trance. When you awaken you think nothing happened and no time passed. You hear your trigger. The post hypnotic suggestion kicks in. You feel a click in your mind. You are a chicken. You enjoy your time as a chicken. Others enjoy seeing you cluck, bob your head, flap your wings, strut, and peck for food. When the hypnotist is ready they snap their fingers and you awaken unaware of what happened. Everyone laughs and tries to inform you in vain. Then the hypnotist snaps their figures and you remember everything. Of course, your friend left a few post hypnotic suggestions in your mind to trigger you later with in case they would like some entertainment at your expense.