It was supposed to be a 6-digit number, but the inventor of the PIN-code reduced it to 4 digits because his wife was sure she couldn't remember more than 4 digits at once.
2. Matches and lighter
It's hard to believe, but the concept of a lighter is older that that of matches.
3. A whole in a lock
It's there so that water doesn't stay inside a lock when it's used outside. This way a lock doesn't rust or freeze.
In ten years the weight of a mattress on average doubles. The reason for that are mites and their excrement.
They were invented around 1904 as clothes for bachelors that didn't know how to sew and couldn't mend their shirts.
6. Medicinal chocolate
Nowadays people drink chocolate milk just because they like it. But the Irish doctor who invented it was selling it as a medicine.
7. Bottom of wine bottles
The hollow at the bottom serves to evenly distribute pressure of the fluid.
8. Dishonest Tic Tac
On a Tic Tac box it's written that it doesn't contain sugar, though it is in fact made of sugar by 98%. The trick is that by American laws a product is considered sugar-free if one portion of it contains less than 0.5 g of sugar. A portion of Tic Tac is 0.49 g.
Wearing rings is not a great idea - it's pretty unhygienic. The number of germs living under a ring on a finger equals the population of Europe: around 730 million.
If you put salt on a piece of pineapple, it will become even sweeter. Try it!
11. Fire hydrants
Nobody knows who invented a fire hydrant, because a patent on it was stored in a patent agency that burned down. Such an irony!
12. A desk
Wipe your desk more often. It is home for 400 times more germs than there are on a toilet bowl.
13. North, south, east and west
If you go north, and keep going north, at some point you will start going south. But if you constantly go east, the direction will never change to west.
14. Peanut butter
Half a kilo of peanut butter may contain up to 5 mouse hair and 150 insect fragments.
Beds are more dangerous than they seem. Every years around 450 Americans die because they fall from a bed.
Our mother have already been born with the eggs that later gave life to us. Cool, right?
17. Bar code
Do you know that a scanner in fact reads white stripes of a bar code, not the black ones?
18. Chocolate cookies
Ruth Graves, the woman who invented chocolate chips cookies, sold this idea to Nestle in exchange for a lifetime supply of chocolate.
M&M’s was invented during the Second World war. The idea was that soldiers could have chocolate that doesn't melt in their pocket.
In USA only around 20 000 people per year call ambulance because they had injured their genitals with a zipper.
2 hours of watching TV per day reduces life expectancy by 1,5 years.
Barbie's full name is Barbara Millicent Roberts.
Chainsaw had been invented as a surgical instrument that was used to widen pelvis during labor.
24. End of a toothpick
The end of a toothpick is easy to break off.
25. Chinese boxes
The Chinese boxes are supposed to be used as plates!
26. Gas station
Don't worry, if you were ever to forget to disconnect a hose and leave the gas station, nothing bad would happen. They has a pretty good safety system.
27. More on bees
A male bee exists only to inseminate the female. In the moment of orgasm it's semen canal bursts and it dies.
Twice less people died of malaria than ever lived on Earth.
Tonic glows in the dark if you use special lamps.
Pig's orgasm may last up to 30 minutes.