How to react to a girl's period

Anonymous
if there's a girl I like or if she's my girlfriend, and she for some reason tells me she's on her period, what can I exactly say in that somewhat awkward moment? is like a hug appropriate, esp. if were really flirty with each other? like an I know you're not really happy right now but I care about you hug?

which begs another question, girls when do you tell a guy you're on your period? and who do you tell? guys you like? or do you never talk about it or do you always joke about it.
Updates
+1 y
I'm very mature with this stuff I meant awkward as its like...one of those oh, OK kind of moments. Like, I wouldn't know what to say. that's all. surely it can't be true that all girls are magically turned into freaks to be avoided when on their period
How to react to a girl's period
32 Opinion