I'm going to joke with my sister and ask her if it's her time of the month.
What is your reason for joking with your sister about her period?
I'm tired of the annoying whining when it comes around. It's getting on my nerves.
It may be annoying to you when your sister has trouble on her period, but periods are no joking matter. Be supportive of your sister and patient with her difficulties.
Gosh stop being so overly sensitive about these issues.
Do your best to be understanding to your sister when she is on her period. It is difficult to understand what she is going through as her emotions are most likely out of sorts. Also, if you are a guy that is yet another reason why it may be difficult to understand her issues.