Generally you can't get people do something they wouldn't do or don't WANT to do. When people usually do something under hypnosis, they are going a long with it because they want to and because it's usually fun. Clucking a chicken, etc etc. Aren't things that they would be afraid of doing without it, because it's something really silly. It's just that with Hypnosis they are more open to suggestion to that one thing or another. Has my Psychology professor has stated. If they think they are going too far, they can and will pretty much stop, no matter what the hypnotist says or does. This was proven on Myth busters when they tried to get Grant to do something silly and minor like drawing hearts or stars on his favorite Battle Bot every time he heard a certain word. It didn't work and all he did every time he heard the word was giggle or laugh. Also most people will remember pretty much everything that happens to them while they are under hypnosis. If they have some amnesia it's usually temporary.