I had an unexpected free morning and ran a race with friends that was advertised as "hilly and challenging". The course was brutal with one flat section of about 100 yards. I'm use to hills in Pittsburgh, but this was really bad- all of us were way over PR. I've seen courses advertised using terms such as "flat", "rolling hills" or "some hills". Is there any general wisdom on what these tersm mean? Although I learned my lesson the hard way, I do think the race was excellent training.