Term used to describe the downward mood spiral that accompanies the hormonal changes that come with PMS. Usually this mood involves feeling that no one likes you, you don't fit in, you're not good at your job, you're misunderstood by everyone, etc. In other words, you feel like crap.
I went home from work crying the other day because I realized that I suck at my job and no one there likes me. I've never fit in anywhere and I've always been misunderstood by everyone.
(A week or so later): I feel great! My period is finally over! I do a great job and everyone loves me! Hey, all that negative stuff I felt must have just been (the) cockabooby!