1 | Don't Toast With Water

You may know of the belief that you should always make eye contact with whom you are clinking glasses, but Germans add another wrinkle to the belief: Bad luck will befall you if there's water in that glass. While some say that's rooted in an Ancient Greek belief about the dead drinking from the River Lethe, it's probably more likely that some Germans just didn't see much fun in toasting with something that's not a big mug of beer.

2 | Don't Whistle Indoors

You've heard of the bad luck that can be invited by opening an umbrella indoors, but you may not have realized that similar dangers supposedly lurk when you whistle. Well, that's a popular belief held among Lithuanians, at least. In their country, the act of whistling indoors is believed to be a call to "little devils" and it's considered rude to do so.

3 | Don't Stick Your Chopsticks Straight Up

In Japan, it's considered not just rude to set your chopsticks in your bowl sticking straight up. It's considered deadly. "It looks like the number four spelled out, and in Japanese culture, four is a very unlucky number—it means death," a Japanese-American woman explained to folklore researchers from the University of Southern California. "If you go to Japan you'll never find anything grouped or sold in fours, it's just superstition, like how in America people are scared of the number 13. Also, you never point your chopsticks at people, like if you're talking at the dinner table. It's rude, and a little threatening."

4 | Don't Kiss Across Thresholds

While one of the big moments of a relationship is a partner carrying their spouse across the threshold of their new home, this area between the outside and inside can also hold danger, at least in Russia. "Never shake hands or kiss across a threshold; you'll become enemies," advises David Filipov, the Washington Post's Moscow bureau chief.

5 | An Itchy Nose Means Bad News Is Coming

A number of cultures held that an itchy nose is a sign of bad luck or bad news being on the way. If you think that's ancient folklore nobody much believes anymore, then would you believe there are actually professional telaesthists, who study itches and what they mean? As The Sun explains, "An itch inside your nose hints at trouble and sorrow heading your way—and an itch on the outside is just as unwelcome. It symbolizes that it won't be long before you're annoyed, cursed, or meet with a fool—which some people prefer to dress up as ‘you will have a visitor'."

6 | Itchy Hands Impacts Your Finances

In Turkey, itchy hands can have important repercussions on your bottom line. As the beliefs go, an itchy left palm means you'll be paying money out or losing money while an itchy right hand means money is soon going to be coming in.

7 | Don't Flip Over Cooked Fish

A common superstition in fishing regions of China, this belief grows out of the idea that turning over a full cooked fish is likely to result in the capsizing of a fishing boat. To get the meat on the other side of the fish, as one book on Chinese dining explains, "gently pull the bone away from the tail end as it is considered bad luck to turn the fish over."

8 | Breaking a Mirror Means Bad Luck

Speculative fiction writer Madelein D'Este explains that a broken mirror is common in cultures throughout the world, from Russians believing the mirror will release evil spirits in the home to Swiss believing the last person to look in a broken mirror is the first to die (or suffer some sort of misfortune). "However, the time period of seven years of bad luck seems to come from the Romans," she explains. "The Romans believed the body takes seven years to renew and similarly, palm readers in China believe that your destiny is renewed every seven years. Others claim the use of the number seven comes Christianity with a link to the seven days of God's creation."

9 | Facing Mirrors Open the Door to the Devil

In Mexico and other areas, it's believed that two mirrors set to face each other—which may look cool and create a pretty weird optical illusion—can in fact open a door to Hell. As Joshua Partlow, Mexico bureau chief for the Washington Postputs it, "they say that if you put two mirrors in front of each other, you open a threshold for the devil."

10 | Don't Buy a Stroller Before Baby Is Born

A common superstition in both the United Kingdom and China is that getting a stroller before the baby is born is bad luck. You can choose it and even buy it, but don't get it delivered until after the baby has safely been delivered unless you want to risk the wrath of the negative forces in the universe.

11 | Don't Laugh as a Hearse Goes By

As the creepy "Hearse Song" explains, "Don't you laugh when the hearse goes by/For you might be the next to die." While that might seem like a quaint throwback of a folk tune, take a look at how your friends react next time a hearse actually does cruise down the block. Chances are you and they will get a little more muted in conversation and a little less lively in laughter. Of course, it's just a myth…but why test it?

12 | Don't Go Directly Home After a Funeral

Another funeral-related fear, this one is more common in the Philippines, where locals subscribe to the idea of "pagpag"—that those who go home directly after a wake can carry bad spirits along with them so they must "shake off the dust or dirt" as the term translates to in Tagalog.

13 | Fear of the Number 13

A number of cultures look upon the number 13 with suspicion and superstition, and the discomfort with the number dates back to the Middle Ages, rooted, as some experts maintain, in the number of people present at Jesus' Last Supper. Many hotels and buildings still skip the 13th floor to avoid freaking out guests and visitors who might still feel a nervousness about the number and party planners will to this day avoid having 13 guests at a table for similar reasons.

14 | Beware Friday the 13th

We've covered 13, but why Friday? For similar reasons, according to anthropologists, who point out that Jesus was crucified on a Friday. Even those who aren't particularly religious have likely thought twice about scheduling an important interview or surgery on Friday the 13th and when something goes wrong, likely have at least considered the cursed date might have something to do with it. Interestingly, other cultures have their own versions of the unlucky day, including Friday the 17th in Italy and Tuesday the 13th in Greece.

15 | Upside-Down Bread Is Bad News

Laying a loaf of bread upside down or serving it upside down in a restaurant in France and Italy is not just bad etiquette; some consider it bad luck. Some assert that this grew from the Middle Ages when the baker would set aside a loaf for the executioner, flipping it upside down to ensure it would go to the right person.

16 | Keep Keys Off the Table

In Sweden, it's considered bad luck to put keys on tables. As one author on Scandinavian practices explains, "the origin of this superstition is that, back in the day, prostitutes used to indicate their availability by placing their keys on the table." Not wanting to mimic such frowned-upon behavior, it became seen as inappropriate for the average Swede to do so, and today you're unlikely to see many people using the dining room table as a place for keys.

17 | Eating Goat Meat Causes Women to Grow Beards

That's what some in Rwanda believed. As some researchers point out, traditional society there imposed many dietary restrictions on women and "It was prohibited for women to eat goat meat under the pretext that it would make them grow a beard."

18 | Bird Poop on You Is Good Luck

This counterintuitive superstition is believed to have originated in Russia, but has gained popularity throughout the west—and anywhere where seagulls and pigeons crowd the skies. While it may have grown out of a desire for those who got "dropped" on to make themselves feel better, it continues to be widely believed by everyone from movie stars to pro athletes.

19 | Stepping in Dog Poop Is Good Luck

France has its own take on this what-seems-gross-is-actually-good-for-you superstition: That if you step in dog poop on the sidewalk (something that can be frustratingly common in Paris), you actually are in for a bit of good luck. But it's not always a good thing. As the belief goes, stepping with your left foot is believed to bring good luck, while your right foot might result in "a life of despair."

20 | May Morning Dew Is Great for Skin

In Scotland and Ireland and elsewhere, locals maintain that the dew that collects on the morning of May 1st (and some say throughout May and into June) has special beautifying properties that leads many to get up early to gather the moisture and put on their face. Some will collect a bunch of it so that it can last them through the next few months and into the following May.

21 | Avoid Black Sheep

Various European countries hold that a black-faced sheep bring bad luck for the rest of the flock. While Scottish farmers are not as likely to hold on to this belief as they perhaps were decades ago, the notion of a "black sheep" in a family or group has certainly continued to be believed and feared.

22 | Don't Get a Haircut on Saturdays

A common belief among Hindus is that getting their hair cut and nails done on a Saturday "brings the anger of Planet Shani (Saturn) upon us," according to one writer.

23 | Trust a Ground Squirrel to Predict the Weather

In this era of Accuweather and 10-day forecasts, the U.S. continues to trust in the weather predictions of a groundhog named Punxsutawney Phil, following the ritual that's been going on in Pennsylvania every February 2 since the late 1800s, in which the groundhog is guided to the top of a stump and "tells" the official whether it saw its shadow—determining if spring will arrive or if there will be six more weeks of wintery weather. It's a ridiculous ritual but everyone involved takes it surprisingly seriously and it's been responsible for its own mini Groundhog Day industry (and a classic Bill Murray movie).

24 | Don't Cut Your Nails at Night

Cutting your nails after dark is considered bad luck in Japan and a bringer of death, according to a common superstition there. The reasons range from the possibility that it might be rooted in an actual fear from centuries before that you could injure yourself in the dark, especially considering the brutal instruments they used back in the day. But it may also relate to a literal superstition that shortening your nails might shorten your life or that it releases part of your soul into the night. Whatever the explanation, it's not a good thing.

25 | Don't Wish Someone an Early Happy Birthday

You'd think wishing someone a happy birthday would always be a good thing. But in Germany, if you do it before the person's actual birthday, you are inviting bad luck—even if it's just a few hours before midnight of the actual day. With that in mind, the country has adopted the tradition of reinfeiern, or "to celebrate into," in which guests gather with the person having the birthday and celebrate as the clock strikes midnight.