I still have those nightmares, too. Where I just found out that I was signed up for a class, and I never attended because I didn't know I was signed up, and the day I find out, I go to class only to find out they are taking the final and I can't answer a single question because I know absolutely nothing about the course material.
I haven't taken any kind of final since the 1990s.
In my dreams, I know darned well I signed up for the classes, but I didn't attend them or start the term papers in a timely fashion. My usual dream consists of a couple classes I actually did attend and do well, but the other couple I totally shined on until it was too late.