12 interesting and fun facts, some of which you may already know.

1. Variable gender

You've probably all eaten grilled oysters, right? But do you know if the oyster you ate was male or female? Actually, its sex isn't always clear; even the oysters themselves might not know. This is because their sex can change with temperature and season.

2. The smallest state in the United States

Many people know that Alaska is the largest state in the United States, but few know which state is the smallest. It is Rhode Island. Despite its small size, it has the longest name: "Rhode Island and Providence Estates State".

Rhode State

3. Going out without underwear

Would you go out without underwear? If you're in Thailand, I advise against it, as it's illegal to go out without underwear there. But one thing I do wonder about is, if you really don't wear underwear, how do people find out?

4. The pig nose on the gas mask

Many people may have noticed that the filter of a gas mask looks similar to a pig's nose. This is because scientists were inspired by the sight of pigs rooting in the ground when they invented gas masks, so there is a basis for the "pig nose" design of gas masks.

5. The burned patents

Fire hydrants are now found in many public places, but no one knows who invented them. This is because the fire hydrant did not protect its patent certificate, which was destroyed in a fire.

6. Don't pick your nose on Saturdays.

You might think, "I can pick my nose whenever I want!" But in Israel, you're not so free, because picking your nose is not allowed on Saturdays. This is supposedly related to a rule in Islam or Judaism.

7. Octopus Superpowers

Octopuses can squirt ink when threatened, pass through holes much smaller than themselves, and open lids inside containers. Moreover, scientists have discovered another superpower: they can edit their own RNA.

8. Bizarre Danish Regulations

From a young age, we are taught to respect and cherish our country's flag. However, in Denmark, there is a rule that is somewhat puzzling: burning one's own country's flag is legal, but burning the flag of another country is illegal.

Danish flag

9. Pigeon droppings as hair dye

Today we have all sorts of hair dyes that can produce all sorts of colors. But in ancient times, there weren't so many options. Women in ancient Rome used pigeon droppings to dye their hair, and it's said that it turned golden.

10. Taxation for single people

Seeing the single tax might make many single people's scalp tingle, thinking, "Being single is bad enough, why should I be taxed?" It is said that the single tax originated in ancient Greece and Rome, and its main manifestation is the deprivation of the right to vote for men who are not married by the age of thirty.

11. Most common wigs

Africans generally have dry, frizzy, and curly hair, making it unsuitable for perming and styling. However, everyone desires beauty, and African women also want different looks, so wigs have become their best choice. Black women have become the largest customers for wigs. The world's largest wig production area is Xuchang, Henan Province.

Xuchang, Henan

12. Yawning is contagious.

Yawning is highly contagious. When you see someone yawning, you are likely to unconsciously start yawning yourself. Some people even feel the urge to yawn just by seeing the words "yawning".