Canobie Corkscrew-- I had ridden it before and found it rough, but when I rode it yesterday it seemed much worse than ever before. I was in pain the entire time and left with an awful headache.
I also found wildcat at hershey really rough, even with the new trains. I was sitting in the back though, so maybe that made a difference.
Oh, and the sidewinder at hershey. I don't think that one really even needs an explanation!