Just be prepared to have a solid answer for "Why psychiatry?", "Why this program?/What are you looking for in a program?", and "Do you have any questions for us?". You should probably be prepared to speak about a challenging and/or noteworthy patient encounter, as well. Be able to give a concise and insightful explanation for any red flags on you application and what you have learned from the experience. Also, as a variation of the first question above, I was also asked several times about any other fields I considered, and it is nice if you can explain why you ruled them out and how psych is a better fit for you.
Other than that, there's no point in trying to prepare for the tough or off-the-wall questions, because these are rare, invariably different, and most times meant to be challenging and surprising. If you are asked something bizarre or that takes you by surprise, take a minute, try and think of an appropriate answer, and stick with it. In my experience, for questions like that, how you react to the question is just as important as how you answer.
Remember, most programs are trying to recruit you. Interviews that are too hard or challenging make the program stand out in a not-so-good way, and tend to be the exceptions and not the rule.
Best of luck to all!
