This idea came to me in a dream:

Pinkie hosts a sleepover (as usual) and suddenly the topic of 'periods' come up. Each of the girls feel compelled to tell their own 'period' story to the rest of the group (mostly since Rarity had told hers first and they all felt pressured). They learn to realize that periods are completely normal and there's no harm in talking about it!

One of these are based on my first experience!
Warning! Contains graphic depictions of menstrual blood and in some cases, an extremely overdramatic Rarity.

Enjoy!!!

RANDOM EDIT: ignore how Rarity's naked for some reason in the cover photo, did not notice lolsiess