All parents know the feeling all too well: When they tuck their kid into bed, give them a kiss goodnight, and go to turn off the light—all for them to ask you 101 questions. Suddenly, they turn into creatures of the night and just want to know everything about how the world works!

Sometimes, all it takes is one single fact to get them to shut their eyes and go to sleep. Of course, parents don’t just have a pocket full of facts at their beck and call at all times.

But now, after a recent Reddit thread called “What mind-blowing (but simple) facts would satisfy a 4-year old daughter’s daily request for 1 fact before bedtime?” went viral, you do! In the thread, people share their favorite fact that will always get a kid to shut u—er, go to sleep when it’s bedtime.

Here are 12 of the best ones. We bet you didn’t know half of these!

1. Elephants

   “Most elephants weigh less than a blue whale’s tongue!”

2. Pineapples

   “Pineapples used to be so expensive that people would rent them as a centerpiece for their party.”

3. Bees

   “Bees tell their friends about good nearby flowers by dancing.”

4. Kangaroos

   “Kangaroos can’t walk backwards.”

5. Butterflies

   “Butterflies smell with their feet.”

6. Japan

   “There’s an island in Japan populated only by fluffy bunnies!”

7. Otters

   “Otters have skin pockets for their favorite rocks.”

8. Stars

   “There are more stars than there are grains of sand on all the beaches in the world.”

9. Chocolate

   “Chocolate was once used as currency (by the Aztecs. more accurately, cacao beans were used).”

10. Guinea Pigs

    “In Switzerland, it’s illegal to own just one guinea pig; if you have any, you have to have at least two. They get lonely!”

11. Worms

    “Worms have five hearts.”

12. Hippopotamus

    “Hippopotamus milk is pink.”

Which fact is your favorite? Do you have any you’d like to share?