Girls: Why do some of you believe you have the right to be bitchy to others while on your period?

I think some girls just use it as an excuse. Like the ones in p.e. who use to say they couldn't be involved in activities because they had cramps. That's bull. Little knowing to them that exercise is actually good for cramps. Go figure. I believe their is more estrogen (i think) that's involved when you're on your period and the little things just get to you sometimes. I use to get real emotional. When I was in high school, lets just say, and a teacher would tell me how to make my essay better to receive a higher grade that would literally make me cry. I was a crier not a yeller when I was on my period back in the day. I am a little more rude now, perhaps time changes you, but it's not an excuse and I have told my boyfriend to tell me to stop when I go off the handle because it's not an excuse. Dang those hormones though! They are a *****!