There are certain facts of life in the modern world. One of them is that no matter what the experience, a man somewhere is going to tell a woman that he knows better. The phenomenon of mansplaining is nothing new. But it’s especially grating when a cisgender man mansplains something that perhaps he doesn’t understand anything about.

It all started when Twitter user @aisghair shared this screenshot on Twitter.

Look at this fucking dweeb pic.twitter.com/2QFqNuqvZz — ash (@aisghair) March 4, 2019

He begins with this extremely suspect math:

“So the average period is between 10-35ml of blood, each tampon holds about 5ml, so 7 tampons per cycle. Lets be generous and say 10 for those ladies with extra juicy uterine lining. 9 periods a year = 90 tampons max.

Before bestowing upon us this “research”:

You can get a 64 pack on Amazon for £7.90 plus shipping. Buy two packs, save on shipping and have 128 tampon for the year, thats about £20 here or their for a years periods.

And finally ending by implying that they’d have enough money for supplies if they didn’t waste so much at Starbucks.

Cut down on your starbucks venti frapps and stop whining. This isnt a first world problem.

People were amused by his equations.

7 Tampons per cycle? pic.twitter.com/Z9xUPyaTnf — Melissa Rose (@Melzyrose90) March 5, 2019

try 7 tampons a day — cat (@maleficusuxorem) March 6, 2019

I am so confused by all of this. 7 tampons per cycle? 9 periods a year? Juicy uterine lining? Has this man ever even met a woman? — Ruthieo ???? (@Roofus890) March 4, 2019

Others couldn’t move past the fact that he apparently believes there are only nine months in a year.

9 PERIODS PER YEAR pic.twitter.com/hkVAycI6yW — O (@itsoliviaaah) March 5, 2019

I’m confused on where he even did the math for this ???? Like… one a month = 9???? — Gecko Dad ???? (@SarahGonzo18) March 6, 2019

Uhmmm helloooo everyone knows periods go dormant for the winter months???????? pic.twitter.com/FzjrtMSjEG — San Holo (@beeeperez) March 6, 2019

If this were true we would have no Libras ???? — Gecko Dad ???? (@SarahGonzo18) March 6, 2019

Lmfao he doesn’t know how many months are in a year that’s for sure ???????? — ₭øυятηєєyy♡★ (@kgilbey93) March 6, 2019

Does he think that a period goes on a holiday? Like it’s getting to Christmas, time for a trip to Mexico. Like it’s an employee ???? — tuck burn is real Yall (@GeoduckErection) March 6, 2019

There were those who zeroed in on the grammatical issues.

All that mathematical effort just for "here or their" to slip in anyway — Dilly (@DylanGification) March 5, 2019

It definitely gave me a bad impression of their attention to detail. — Daily Pedantry (@DailyPedantry) March 5, 2019

And there was this well-reasoned takedown.

it's medically dangerous to wear a single tampon for more than 8 hours, so let's call it 6 hours/tampon. let's call it 5 days of your period (altho lots of people have 6-7 days). that's at least 20 tampons per period. TWELVE periods per year makes a minimum of 240 for the year. — ella mayo (@ermahgerd_hi) March 6, 2019

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. an average person would get about 450 periods in their lifetime. you end up with about $22,500 in a lifetime — ella mayo (@ermahgerd_hi) March 6, 2019

there are tons of people who can't afford to spend 50 bucks a year. even if they can afford it, period-related items shouldn't be treated like just regular ol' products. — ella mayo (@ermahgerd_hi) March 6, 2019

But most were just skeeved out.

For real though. Someone call the police on this dude. — Sean Lewis (@seanglewis) March 5, 2019

This fr hilarious ???????????????? — Jasmine roper (@jazzieboohouse) March 6, 2019

Have you called them yet? Have they got the warrant out ready? ???????????????????????? — Michelle brady (@Sagitarrius1968) March 6, 2019

Men. What will they think of next? And who will they find it necessary to instruct?