Bill Joy's Nightmares
In Outliers, Gladwell quotes Bill Joy commenting about how they had nightmares about forgetting to go to class or forgetting they were even enrolled in a class.
I've had multiple 'Oh, snap! Wasn't I enrolled in an econ course?' moments toward the end of the semester. In fact, this year I've had at least one dream about completely forgetting about a biology course and a philosophy course for pretty much an entire semester. That was this year, and I haven't been in school since 2005.
Luckily, the reality is that I've missed class three times in my life: once because I was giving blood for six hours (long lines on Sept. 12), once because I was in a ballet performance at the same time, and once because I thought it was Monday or Wednesday, not Tuesday.