1. CZECH REPUBLIC: smacking women with a special whip at Easter.
2. UK: saluting lone magpies.
Magpies are ill omens in British folklore - it's "one for sorrow, two for mirth," according to the old Lincolnshire nursery rhyme. That's why, in many parts of the UK, if you see a single magpie you can mitigate the bad luck it brings by greeting it with the salutation, "Good morning Mr Magpie, and how is your lady wife today?"
3. NETHERLANDS: congratulating the entire family on someone's birthday.
4. POLAND: applauding when the plane lands.
5. SCOTLAND: Wearing skirts and reciting poetry once a year.
6. RUSSIA: having a sit-down before leaving on a trip.
7. USA: listening to a weather-forecasting rodent.
On 2 February, the people of Punxsatawney, Pennsylvania gather to observe a groundhog called Phil emerge from his burrow. If Phil sees his shadow, there will be six more weeks of winter. If not, you can expect an early spring. Groundhog Day dates back to 1886, and apparently there has only been one Punxsatawney Phil. He owes his great age to a closely guarded punch recipe.
8. ESTONIA: Going into the forest with your crush to "look for fern blossoms".
9. AUSTRALIA: Celebrating the Queen's birthday with a public holiday in June and September. The weird part? The Queen was born in April.
10. AUSTRIA: Pulling fingers.
11. DENMARK: Throwing cinnamon at single people.
12. FRANCE: buying funny hats for your unmarried friends.
13. GERMANY: following a sock-garland to your birthday party.
14. GERMANY: Cleaning on your thirtieth birthday.
15. FINLAND: Competitive wife-carrying.
16. ALSO FINLAND: Athletic boot-throwing.
17. MEXICO: Shoving your face into your birthday cake.
18. ALSO MEXICO: Throwing money for children.
19. JAPAN: Following a giant penis through the streets.
The festival of Kanamara Matsuri dates back to the 17th century. Revellers dress as penises, eat penis-shaped sweets and create giant iron penises to carry through the streets of Kawasaki. It honours the legend of a woman who had a demonic toothed vagina that ate men's penises, and it remained undefeated until a metal-worker built a metal penis that broke the demon's teeth.
Inspired in part by this Reddit thread.