1. When a woman's period begins at an inopportune time.
2. When a woman's period blood comes out all clotted and chunky, and a man observes it.
3. When a woman's vagina bleeds, and somehow the blood gets on your mother.
1. I was going down on that bitch when suddenly instead of pussy juices, blood started gushing all over my face giving me a clown moustache. That's some unfortunate menses.
2. That meatball stew was some unfortunate menses.
3. My mother hates unfortunate menses, but your mom loves it.