The answer is flunking a class. Flunking a class during college years is the most stressful item in the College Undergraduate Stress Scale (CUSS). Flunking a class means failing it, which results to more stress, it will make you take it again, but it depends on that subject’s availability. You’re chances of graduating early may be hindered because of a flunked class. There is nothing more stressful than flunking a class.