How does ?????

How in the heck do boys no about periods? They be getting on my nerves i was @ school and i had a pad in my purse and my purse fell it was so embarrsing!! Anyways i picked ^ the pad and then he said KIMBERLY STARTED HER PERIOD HEHEHEHEHEHEHEHEHEHEHE. I was like you been watching 2 much t.v, then he said they bleed from their virgina hole ewww! HE IS 12 I THINK AND THANK U HE DIDNT TELL MY BOI FRIEND I WAS SO PIZZED OFF @ HIM!!!!