First, I'd have to say that, when the interviewer asks you about your hobbies, don't list "surfing the internet" first. That may be true, heck, it probably is for most people today, but we do not want to hear that. We want at least the pleasant fiction that you are well rounded. And if, on the topic of being well rounded, you say in your essay that a given subject, say Oriental ceramics, is a vital interest of yours, and that you love to talk about them, you should actually be able to talk about them. I'll ask. And yes, that was supposed to be an easy question.
I try not to be mean. I do, however, want to put the you on the spot, and make you sweat a little. Medicine is a horrendously stressful job, and the five minutes of nervousness you have in this warm little room is nothing compared to what you'll face (if you are successful) in four years when there is a patient in front of you coding. I've never been in that situation, but I was stressed the few times I've seen it just watching my residents. And if you can't take my question asking how, exactly, you manage to volunteer 50 hours a week and still find time to study, then maybe medicine isn't the right place for you. Ditto if when I ask why you are interested in medicine, the answer is not only not convincing, it sounds like the question surprised you.
The other topic I love to cover is ethics. As I explained to an interviewee after his ordeal in front of me today, there may be a wrong answer, but there isn't really a right one. I just want to surprise you and make you think in front of me. The best way to do that is to ask something totally unexpected. Here's a tip: pausing before answering is fine. In fact, it is way more impressive than the other guy who shot from the hip and rambled for about two minutes about nothing. I'm a past master at talking without saying anything, and trust me, I can see it in others.
The process does bring up ethical dilemmas of my own that I admit I didn't expect. For instance, one of the people I interviewed was a singularly attractive young woman, one whom I probably would have asked out for drinks in another setting. (Maybe, I'm just saying.) Anyway, because I found her attractive and interesting, it would have been very easy to be softer on her than on another applicant.
Fret not, gentle reader, I neither abused my power by asking her out, nor did I succumb to the temptation not to ask her tough questions. The whole thing reminded me though, of a class I had my first year discussing how we are to deal, as physicians, with such situations. For doctors are human too, and patients can be repellent or alluring, and similarly, it is inappropriate and unethical for us to allow those emotions to affect the way we do our job. Simply denying them is impossible, but we do need to recognize them and work past them. I definitely don't have this whole doctor thing figured out, but I am learning. That's positive I guess, with only 106 days left before it isn't pretend anymore.