Sneezing Monkey - Buddhika Weerasinghe/Getty Images

Someone sneezes, and you automatically respond with “Bless You” or “Gesundheit”. This happens millions of times every day, but most of us have no idea why we are saying it, or what it even means.

When someone “sneezes” out of their behind, we don’t say anything. Well, not if you don’t count “you’re nasty”, anyway…

While the exact origins are unknown, there are a few theories. Here is what is known:

The phrase "God bless you" is attributed to Pope Gregory the Great, who uttered it in the sixth century during a bubonic plague epidemic …which, coincidentally, is what claimed his predecessor. While it didn’t always mean death, sneezing was an obvious symptom of one form of the plague.

The German word "Gesundheit" literally means "health." The idea is that a sneeze typically precedes illness. It became a common saying in the USA in the early part of the 20th century, when German immigrants brought it over the Atlantic.

The majority of nations around the world have some form of blessing sneezers. The Romans would say "Jupiter preserve you" or "Salve," which meant "good health to you." The Greeks would wish each other "long life." Arabic countries say, "Alhamdulillah," (Praise be to God). In China, they say "bai sui" (may you live 100 years) to children. Russians have two different sayings; "bud zdorov" (be healthy), and "rosti bolshoi" (grow big). Hindus say, "Live!" or "Live well!"

It’s commonly believed that all of these responses come from ancient superstitions. Some cultures believed that a sneeze is the soul leaving the body through the nose, so you say “bless you” to stop Satan from claiming it. Other cultures believed that evil spirits use the sneeze as an opportunity to enter a person's body. And, of course, there were the ignorant few who believed that the heart momentarily stops during a sneeze (it doesn't), and that saying "bless you" was a way of welcoming the person back to life.

We now know that sneezing is a reflex action and is most often the sign of something relatively benign, such as a cold, allergy, being outside in the sunlight or from smelling a strong odor. Still, we continue to keep this tradition alive, but now-a-days, "bless you" is more a sign of good manners than a shield against death.