When I was in grade school, a number of students were called on to take part in a hypnosis seminar. A minute into the hypnotists presentation, I was asked to leave as I was the only one who wasn't being hypnotized.
If I recall correctly, there were 15 of us up there to begin with.
A couple of the others said they weren't hypnotized, but the important part is the majority said and acted as if they were.