Coincidence?  Or based on stereotypes about women and, especially, PMS?

From Dr. Grumpy, sent in by Dan S.  Also from Dr. Grumpy, the shaming vending machine.

Lisa Wade, PhD is a professor at Occidental College. She is the author of American Hookup, a book about college sexual culture, and a textbook about gender. You can follow her on Twitter, Facebook, and Instagram.