I have the same nightmare once every year or two when I allow myself to go to bed with some stressor on my mind. I show up in a room with 10 minutes left to take a test that will clearly take me hours to finish and the results will decide the fate of my degree, if not career. It's just like the scene in Risky Business, which is probably the genesis for it. Ah, Rebecca DeMornay.
College was almost 30 years ago for me. Hate to break it to you, but this nightmare never ends. Enjoy.