Graduate level courses are surreal. Professors assign nearly impossible homework assignments and projects. The exams make you break out in sweat just thinking about them. At the same time, you are often able to just sketch out solutions since it is assumed you could carry out the details if you really wanted to; weeks pass where you just hold classroom discussions instead of doing "real" work.
The exams in an analaysis of algorithms course I took several years ago were particularly interesting. Consisting of only one or two questions, they asked you to perform analysis on an algorithm you had probably never seen before. Consequently, there wasn't much you could really do to prepare for the exam.
This all led to a strange incident on the first exam day. The professor, who shall remain unnamed, was handing out the exam papers at the start of class. As he did so, one of the students raised his hand and asked, almost seriously, "Is this exam open book?".
The professor casually replied, "Um, sure, why not?"
Needless to say this didn't make the exam any easier. Somehow, I miss those days.