This guy tried to 'mansplain' tampons to his female friend, and Twitter absolutely wrecked him

There's a very simple rule to follow when it comes to making statements on the human anatomy: if the issue you're talking about is not one you have personally experienced, you're probably not going to know more about it than someone who actually deals with it on a regular basis. Cis men - we're mainly looking at you, here.

I'm not sure quite what it is about the female body that makes some guys think they know more about it than, you know, an actual woman, but it seems all too common an occurrence that random men on the internet like to pipe up with things they think they know about us.

Take this guy, for instance, who thinks he's cracked the math behind that experience which is oh-so-not-familiar to men: periods.

Obviously, there's a lot to unpack here. But let's start with the basics.

This guy thinks we get nine periods a year. Nine. With the average cycle lasting for 28 days, people with uteruses actually get periods more like 13 times a year - so that's just plain wrong, right from the offset.

Now let's take a look at this claim that the average period is between 5ml and 35ml per cycle... 'cause it's blatantly wrong.

And, even if it was right, let's consider for a second that this dude thinks we can wear one tampon for 24 hours (assuming a period lasts seven days a week). This is incredibly dangerous. Tampons should never be worn for more than 8 hours at a time, as they can lead to potentially fatal TSS (toxic shock syndrome). Plus, it's totally impractical. Oftentimes, they become uncomfortable after a few hours, and can start to leak before that, even.

Now let's get down to these claims about tampon costs. This dude thinks he can cover a year's worth of menstruation for £20 ($26). Twitter user @ermahgerd_hi explains why that's a lie.

"Let's call it 5 days of your period (altho lots of people have 6-7 days)," she begins. "That's at least 20 tampons per period. TWELVE periods per year makes a minimum of 240 for the year. We're gonna add in a factor for people who change it more often than 6 hours. You'd buy 5 packs (320 tampons). By the cited $7.90 per pack + shipping, we get ~50 bucks."

This works out at about $2,000 across a lifetime - and that's the minimum. A lot of people will need to spend more, either because they have heavier/more frequent periods, have sensitivities to cheaper brands, or, you know, just don't like the discomfort of having the same tampon in for six whole hours. Oh, and let's not get started on the cost of painkillers, the money spent on new underwear any time a pair gets inadvertently ruined, or the wages lost when we can't get out of bed to go to work because of debilitating cramps.

Needless to say, Twitter tore him a new one.

So no, random internet man, we can't just lay off the frappuccinos and "stop whining", because this is a serious cost to literally half the population of the world. How about you lay off the mansplaining and listen to a woman for once?