I was a bit precocious when I was in the first year of junior high school

Twelve or thirteen years old and I understood everything
Once during class, I left a lot of blood below
My pants were stained red
But I remained calm and unhurried
While my classmates were all very scared
I struggled for a long time
Trying to explain to them
What a menstrual period is
Until the teacher came over and said
Boys don't have this thing
Hurry and go to the hospital