The four o'clock freak-out occurs on Sunday afternoons before the start of a week of college work. You suddenly realize that it is already four o'clock (the day is almost over!) and you have not done anything in preparation for the week ahead. Instead you have wasted the time you had to do work by surfing facebook, napping, and shopping. This catastrophe could be followed closely by the five o'clock freak-out, which sneaks up while you are wasting more time freaking out.
I spent Friday and Saturday having fun, with good intentions to study on Sunday. I slept in late, putzed around the house until I realized it was FOUR O'CLOCK and I still had to write three papers and put together a presentation, suddenly my stomach dropped, my heart started pounding, and I knew I was experiencing the Four O'clock Freak-out!