Removes pain, period.

I know all about abdominal pain, so when young ladies complain about their lady-parts-go-ouch days, I sympathise. I mean, being a sympathetic guy I'd sympathise anyway... because that's who I am... but I digress; I spend a lot of my time in considerable stomach pain, so I understand. It's a hateful, spiteful kind of pain, the kind that makes you want to wave a fist angrily and scream, "How long, O Lord?" (Habbakuk 1:2).

But the period has an upside, at least, it does if you are me, and of course, the obvious upside being that I'm not the one experiencing the period. But then there's the fact that I get to pet my lovely girlfriend, and share chocolate with her, as well as stories, snuggles, advent candle watching and Russell Howard's Good News. And of course we have an excuse to do all that, because she's on her period and needs some TLC. I, of course, am not complaining.

And then there are the sexytimes. Obviously there's little penetration to be done when the young lady is 'on' (although it's not unknown; I've had period sex; seems to work just fine) - and licking out sans tampon (not being a lady I don't actually know all the mysterious practices, but I know you can use a tampon or a sanitary towel) makes me feel a little bit like Dracula - but there's always licking to be done with a tampon in, too.
In fact, that's convenient. You've got a little blue string to hold onto, which is also a useful placefinder when it's pitch dark. The clitoris is also still available, and free for stimulation... oh, and the tampon soaks up most of the mess, too. I fail to see any faults... except for the whole no-penetration thing. But I can deal with that.

I didn't realise the orgasm would be that intense, either. But, as I said... I'm not complaining. Neither, come to think of it, is she.