Kahoa Interview Question

I was shown a short Java program, asked what it would do, and then shown it did something totally different. The interviewer then said, "Don't worry, this is a tricky problem no one gets right the first time. How would you figure this out?" I would step through it in a debugger, I replied. "Fine, let's do that." The interviewer watch as I debugged the program and figured out why it was acting so weird. He got to see how I approached problems and that I knew my way around a debugger.