I just don't get the "shock" interview mentality. My boss did this to one of my co-workers. He brought him in for an interview and about half way through spun around in his chair (he was sideways to the guy) and started bouncing a ball of the wall and catching it. He did this for about 10 minutes.
That shows a complete lack of respect. I would have (politely) told him so and ended the interview. I would not be comfortable working for someone who can't look me in the eye and gives the appearance of being bored.