We all go through life mispronouncing or misunderstanding things once in a while. The thing is, sometimes we don’t realize our mistake until much, much later in life. Once we’re able to grasp the reality, we wonder how many other people thought the same thing as you—or were you the only one?

Chances are, you weren’t. A recent Reddit thread titled “What really obvious thing have you only just realized?” gained traction when people started commenting on all the “obvious” things they suddenly realized—but most of these were things other people were mind-boggled to learn also.

Here are 13 of the funniest things people just realized.

1. What the phrase “mint condition” means

   “The phrase mint condition means like new because it’s the condition coins leave the mint in.”

2. How to use deodorant

   “To take off the plastic piece on top of deodorant you just simply twist the bottom a few times.”

3. What the division symbol stands for

   “The division symbol (÷) is just a blank fraction with dots replacing the numerator and denominator.”

4. How to use a towel

   “You’re supposed to use the towel to dry yourself after a shower. I was just wrapping it around myself and sitting /walking around in it until I air dried.”

5. Where the little piggy actually went

   “This little piggy didn’t go to the market to do any shopping.”

6. How to make coffee

   “I used to always pour water into our coffee maker one glass at a time. It was such a pain, especially to fill the reservoir to the number of cups I wanted. Until I realized I could just fill the carafe with water, which has the exact same measurements, and pour the water in that way.”

7. What a “birthday suit” is

   “I realized that to be in one’s birthday suit it means to be without clothes. I thought for the longest time it was a specific set of clothes you would wear on your birthday each year. I found out when I asked, ‘what happens when you don’t fit in your birthday suit anymore?’”

8. How a vacuum works

   “The reason the cord hook on the vacuum spins is so you can take the whole cord off at once instead of unraveling it one loop at a time, like I have been my whole life.”

9. There’s only one astigmatism

   “I thought astigmatism was A stigmatism. So I thought you could have two stigmatisms.”

10. Who Santa Claus is in that song

    “The mommy in that Christmas song wasn’t cheating with Santa but instead, it’s the dad dressed in a Santa Claus costume. That’s why ‘I saw mommy kissing Santa Claus.'”

11. The significance of this cartoon’s name

    “That Jessica Rabbit is not a rabbit, but took Roger Rabbit’s last name.”

12. What “Tinder” means

    “The app Tinder is called tinder because it means to spark a flame. Just like sparking a love interest. There is even a fire symbol. I felt stupid.”

13. What SpongeBob’s town homes are made of

    “The houses in Bikini Bottom are car mufflers…”

What painfully “obvious” thing did you just realize later on in life?