Do men do that on purpose, or is it just so ingrained in them from babyhood that they can't help it? Ingrained in them that women's bodies do this "disgusting" thing every month or so, and they have to put up with it, but they want to know nothing about it, not even that it is currently happening.
It's not like men don't do or say disgusting things (often on purpose), but for some reason, menstruation is too much for them. They'd rather hear about the size, shape, consistency and smell of your last bowel movement.
Do men know that every time they say get that look on their face (the cat puke look), or say "TMI" about the littlest mention of a period, women feel BAD about themselves? Like seriously... it makes us feel bad about our existence as women. Some of us, many of us, anyway. Do you know that? Do you do it on purpose? Because we don't have periods on purpose. In fact, most women would love to never have another one again. Not just because they make us feel like crap, but because men make us feel like crap for having them.
So next time your wife or any other woman in your life says those four innocent words, "I got my period," remember a couple things: First, she's not trying to offend you, she's trying to prepare you. Second, she has already steeled herself up against your cat-puke look, but that doesn't mean it doesn't bother her or hurt her. And third, all she wants you to say is "oh, okay."
And loose the freaking cat-puke look.