Maybe the 9th is all you can eat at the local curry house? Or payday so theyre getting a takeaway? Periods come 4 weekly not on the same date each month ffs!
Honestly the thing that pisses me off most is the fact that they have been lying in bed all day, actual women can't take a day off to lie in bed each month with period pains ffs! We have to get on with it, I remember throwing up each month in the school toilets with period pain but I couldn't afford to take a day off school every 4 weeks. Imagine if every woman spent the day in bed when they had period cramps, the world would just stop.
And also the worrying lack of knowledge about female biology and how periods actually work, how little these people actually know about the female body.