What's some common knowledge that you just found out recently?

Not quite recently, but after skating through high school and most of college I learned that if you read through your notes before a test you remember more things. I also learned that this is referred to as "studying".

That annoying character in The Land Before Time is not named Sarah.

Her name is Cera. As in CERATOPS.

That you aren't supposed to rinse immediately after brushing your teeth. It's better to wait 15 minutes to let the fluoride strengthen your enamel.

Been brushing the wrong way for 30 years, apparently.

The guy who runs Reddit is an utter douchebag.

Common sense is not common.

I spent 30+ years thinking that a pony was a baby horse rather than a smaller type of horse. You know how cats have kittens and dogs have puppies? Well I thought horses had ponies.

Even all the times that Lisa Simpson wanted a pony, I just thought it was similar to how a kid might want a puppy.

I knew about this on some level before, but the recent posts have given me a better understanding on how in some countries people need expensive third party software to pay their taxes.

A pancake is a cake you make in a pan.

It broke my mind when I learned that one

prima donna != pre-Madonna

People know less than they think they do, which is why everyone calling everyone else morons is probably correct.

most are in the past year kind of recent:

... that there's a group of people who pronounce "gif" with a "soft g" sound like "jif"

... that Taylor Swift is that popular, she is seen as a political threat for her influence

... also armor bags for kids and shooter drills like it is some kind of natural disaster

That when cooking anything with leftover grease you should always dispose of the excess grease in an empty container and trash it instead of putting it down a drain.

Also that it's best for your pipes to put your used toilet paper in a trash can instead of flushing it.

That not all drinks get you drunk the same way.

A friend of mine: liters are not the same as kilograms. She's 30...

Maybe this more of a misheard lyrics thing, but for a long time I thought "noxious gas" had to do with nitrogen oxides (NOx), and then spread to other metaphorical applications like "noxious weeds" and so on.

stimulations needed to come