Heh. My roommate and I tend to get into massively bitchy fights around our periods, too. I'm not entirely convinced it's just because of hormones, but I think the irritability makes any other issues that much harder to deal with calmly.
I do know that my boyfriend really appreciated it the other day when I told him that I wanted to discuss some issues with him, but that I didn't want to have the discussion just yet because I'm pretty pissy right now. He was quite grateful that I'd pointed it out myself, instead of him silently biting his tongue about it.
Vix for short.