Fear of Friday the 13th is also known as paraskevidekatriaphobia

Do you suffer from paraskevidekatriaphobia? If so, you’re not alone.

Fear of Friday the 13th dates way back. However, the exact origins of this superstition are unclear. Some suggest that it comes from the tale of Jesus’ last supper and crucifixion. Others claim that it stems from events on Friday 13, October 1307, when hundreds of Knights Templar were arrested and crucified.

Whatever the reason Friday the 13th became unlucky, it’s far from the only puzzling superstition in the world. Here are 10 others.

Receiving a knife. Has someone given you a knife as a gift? You better give them a coin in exchange, or else your friendship will be ruptured.

Opening an umbrella indoors. Why does opening up an umbrella indoors bring bad luck? The belief likely dates back to when the earliest umbrella models were sold. Their hazardous opening mechanisms and metal ribs presented a risk for fragile belongings when opened indoors.

Walking under a ladder. When you step under a ladder, some believe that you desecrate the Holy Trinity that the object forms with the ground and the wall. The ladder is, moreover, associated with death by hanging and Jesus’ crucifixion.

Breaking a mirror. In Rome, it was once believed that mirrors reflected the soul. If you broke a mirror, you damaged your soul and suffered seven years of bad luck. Why seven? The Romans believed that this was how long it took for the body to renew itself.

Cutting fingernails at night. According to the Japanese, if you cut your nails at night, you won’t be at your parents’ side when they die. Indians, on the other hand, believe it causes you to lose small, valuable objects.

Installing witch windows. In Vermont, and a number of other places, the gables of some homes have windows tilted 45 degrees to prevent witches from breaking in with their broomsticks. They’re aptly called witch windows.

Turning a loaf of bread upside down. Placing an upside-down loaf of bread on your table invites the devil into your home. This superstition dates back to the Middle Ages when executioners were presented with an upside-down loaf of bread on execution days.

Putting your purse on the ground. In Brazil, you risk ending up impoverished if you put your handbag on the ground.

Seeing a black cat. Black cats were believed to be witches’ companions and therefore evil. This was largely due to black being associated with the devil. In some cultures, black cats are thought to be harbingers of death.

Running an electric fan. In South Korea, running an electric fan in a closed room with closed windows is thought to be potentially fatal. There’s even a name for this phenomenon: Seonpoonggi samangseol, or fan death.