When my laboratory held the meeting today, a female researcher went to a toilet. Because I also felt the need to urinate, I went to a toilet after her. Then, I didn't notice anything strange.
After a while, I went home with my senior researcher. Then, he suddenly began to say "Do you remember the event that girl went to the toilet? I guess she would be suffering from menstrual pain, judging from her having patted on her waist. So, she will have menstrual pain on November 11th."
His ability to find symptom of females' disorder is better than any other acquaintance of mine.
