Even if you don’t consider yourself superstitious, there’s a good chance that superstitious beliefs have still worked their way into your life. For example, maybe you try to improve your luck by knocking on wood or picking up pennies. But when it comes to creepy superstitions, these mild practices pale in comparison to the scary things people around the world believe can happen when you defy a superstition.

Have you ever wondered where superstitious beliefs originated? Well, we’ve done the work for you — and you don’t even have to cross your fingers, clutch a rabbit’s foot or throw salt over your shoulder to explore the origins of these 10 creepy superstitions.

1. The Number 13 Is Unlucky

At least 10% of the U.S. population fears Friday the 13th or the number 13 when it comes to dates for weddings, travel and other occasions. In fact, some high-rise buildings don’t contain a 13th floor, according to History.com. Some theorists speculate that the fear of 13 stems from Judas Iscariot’s arrival as the 13th guest at the Lord’s Supper. Others pin the superstition to the ancient Norse God Loki, who arrived as the 13th guest at a dinner party, upsetting the other gods and introducing evil and turmoil into the world. However, the origin may go back even further, to the preference in some ancient civilizations for the use of the “perfect” number 12 in calendars and measurements, casting a shadow over the less-auspicious number 13.

Creepy Superstition 13th Floor

2. Breaking a Mirror Brings Seven Years of Bad Luck

You may know that breaking a mirror doesn’t really bring bad luck, but wouldn’t it make you at least a little nervous if a mirror falls from your wall and shatters? This old superstition originated with the Romans, who believed that our soul could be seen in a mirror. They believed that damaging the mirror would damage the soul for seven years. Another Roman origin is the belief that our soul renews every seven years, so if you break a mirror, your soul receives a seven-year sentence of bad luck.

3. Walking Under a Ladder Draws Misfortune

This superstition originated with the ancient Egyptians, who believed that triangles were sacred because they signified the trinity of the gods. So, someone passing through a triangle desecrated the gods, inviting misfortune. Another theory is that criminals sentenced to hanging had to climb a ladder to the gallows, and then the spirit had to descend the ladder after dying, leaving the person’s lingering, restless soul lurking beneath the ladder.

4. Tuck Your Thumbs in at a Cemetery

Nothing raises old, creepy superstitions from the dead like wandering around a cemetery. And if you’re attending a graveside service or standing near a funeral procession, you might want to take a few extra precautions. That’s according to the Japanese superstition of tucking your thumbs into your fist to protect your parents from death, since “oya yubi,” in Japanese means “parent” (oya) and “finger (yubi), hence the parental thumb.

5. Don’t Trim Your Nails After Sundown

You may want to cancel next week’s evening pedicure once you read the origins of this superstition. In Turkey and India, there is a superstition that cutting your nails after sunset will bring bad luck. Japan takes that creepy superstition seriously, warning that trimming your nails at night can cause premature death. But the Koreans go all out, believing that discarded clippings will be eaten by rats who morph into monsters to terrorize you as you sleep. In other words, you might want to consider trimming those toenails on a sunny afternoon instead.

6. Singing at the Dinner Table Summons Evil Spirits

Next time you feel like breaking out into song over the mashed potatoes, you may want to hold off until you leave the table. Otherwise, you could attract evil spirits, according to a Dutch superstition that’s also common in Bohemia and North Carolina. The origins of how this belief came about are uncertain, although some speculate that someone may have wanted to silence a dinner mate with a less-than-melodious voice.

7. Whistling Attracts Tragedy

If you’re one of those people who just can’t get the whistling thing down, you may be luckier than you think. In Turkey, there’s a superstition that whistling at night summons the devil. In Estonia and Latvia, the superstition takes a different twist. There they believe that whistling indoors can bring bad luck, causing the house to burst into flames. Some Russians believe that whistling can cause financial ruin. So next time you feel like whistling the day — or even worse, the night — away, maybe hum a few bars instead.

8. A Black Cat Crossing Your Path Is Unlucky

The ancient Egyptians revered cats, linking the sleek companions with deities, women and a prominent place in the household. Cats toppled from their revered pedestals around the 13th century, however, when Pope Gregory IX issued a warning against having or associating with cats. He portrayed the felines as Lucifer in disguise, cavorting with witches to place curses while purring beside a bubbling witch’s cauldron.

9. Hold Your Breath When You Pass a Cemetery

You might think that practicing deep breathing when you pass a cemetery on the way to work is a good way to get grounded. But you might also inhale an evil force or a recently departed spirit looking to take up residence in your body, according to an old superstition with origins in the South. The superstition, which advises holding your breath when passing a cemetery, is still common today in some Southern states.

10. Never Rock an Empty Chair

You may be tempted to rock that empty rocking chair just for the heck of it. If you do rock an empty chair, however, you may as well hop right on and rock to your heart’s content with the evil spirit you just invited into your life. That’s according to another Southern superstition. In a different version, standing up from a rocking chair that you allow to keep moving ensures that you’ll get sick within the next year.

Now you know the origins of enough creepy superstitions to impress your friends, but there are still plenty we didn’t cover. Are there any superstitions that give you pause, at least just a little? If so, share them with other readers in the comments.

Who knows? You may keep someone from picking up an evil spirit passenger or attracting bad luck — or you could just make someone the life of the Halloween party.