I just did my off-campus interview with an alum. Lucky for me, I had been prepping for every question I was asked and I felt that my answers came out sincere and not rehearsed.
In no particular order, here are the questions:
1. Tell me about yourself (essentially, walk me through your resume)
2. Why Booth?
3. Why an MBA?
4. What is your plan for after graduation?
5. If you could change anything about your career up until now, what would it be?
6. How would your friends describe you?
7. What are your plans if you don't get into Booth? Will you apply again next year?
We only had 30 minutes for the interview, so I was only asked those 7 questions and I was allowed time to ask some of my own questions. Remember to prepare some good questions because I really got a deeper sense (beyond what I already had) of the Booth alumni community from one of the questions I asked.
In all, it really didn't feel like an interview; it was more like a conversation. So, do your prep work, practice out-loud in front of your mirror and don't sweat it!