Pine trees are covered in mold. While this isn't an issue when they're outside in the fresh air, mold thrives in your nice central-heated house. After just two weeks inside, the number of mold spores in the air increases more than sixfold. And if the knowledge that right now you're inhaling thousands of tiny, fuzzy bits of fungus isn't enough to make the germaphobes among you hold your breath until you're blue in the face, don't worry, it gets worse.

Photos.com

While most people might just come down with a stuffy nose and a bad cough, all that mold can be much more dangerous for some. One study tested various kinds of pine trees and found 53 different types of mold, 70 percent of which could lead to respiratory problems, up to and including bronchitis and pneumonia. You might recognize those as dangerous illnesses that can land you in the hospital and/or kill you dead.

And if you think you're going to outsmart Death by setting up a fake tree, good luck. While those plastic abominations are a bit better for your health, they're still covered in a year's worth of dust, all of which gets dispersed in one room when you set it up and can lead to an asthma attack.

According to a Consumer Reports poll, 90 percent of people have at least one thing that gets them down or stresses them out over the holidays. Some of the major things that annoy people are obvious, like crowds and traveling, but every year millions of people are also driven to distraction by Christmas music and "having to be nice," because apparently that lie about Santa watching you that your parents told you as a child sticks around well into adulthood. Another poll found that the financial pressure of Christmas is so intense that 45 percent of people would rather skip the holiday than deal with the bills.

Photos.com

And if you're feeling smug that you get around all this stress by not celebrating Christmas because you are irreligious or practice a different religion, don't worry, it still manages to mess you up, too! One study found that the presence of a Christmas tree in a room made non-Christians feel subconsciously excluded and less happy than when there were no signs of the holiday around. So by making you feel like an outsider, Christmas is making sure that everyone is equally depressed at this supposedly joyous time of year.

Everyone expects to gain a pound or two around the holidays, but what is shocking is just how badly and how quickly you can become unhealthy. Boxing Day is one of the most dangerous days of the year for people with heart problems, and after the amount you eat and drink on Christmas, you just might fall in that category.

Photos.com

One study in Britain found that people eat their daily recommended calorie intake by 2 p.m. on Christmas Day. You might recognize 2 p.m. as before you even really start eating. By the end of the day, expect to consume 7,000 calories. This might be why people gain an average of 6 pounds in the nine days between Christmas Eve and New Year's.

And that doesn't even begin to include the leftovers ... or the alcohol. Drinking increases over 40 percent in the U.K. and almost 30 percent in the U.S. over the holidays. All this unhealthy food and drink can increase your blood pressure, and the added stress can combine to make the perfect storm for a heart attack -- the number of heart-related deaths increases by 5 percent over the holidays.

Photos.com

Then there is the fact that no one wants to mess up Christmas Day with their chest pains. So logically, instead of going to the hospital when they first start feeling unwell, people tend to wait until December 26 to see a doctor, by which point whatever is wrong with them is worse than it was the day before. And even if you don't personally have to worry about keeling over due to heart problems, if anything else goes wrong, expect to wait a long time to be seen in the emergency room the day after Christmas. Many hospitals say it is the busiest day of the year for them.

Sure, you probably can't take out all your holiday anger on your family without ruining Christmas, but you can scream at the guy who cut you off to your heart's content. Just keep in mind that there will be repercussions. Thanks to the fact that 32 percent of drivers become more aggressive around the holidays, the number of accidents increases almost 20 percent in the month of December, and that doesn't even include the fender benders in crowded parking lots that aren't reported.

Aboutaboyo/Flickr Open/Getty Images

With driving being so stressful, who could blame you for wanting to take the edge off with a cheeky drink before you hit the road? The fuzz, that's who. DUIs skyrocket between Thanksgiving and New Year's, with the number of drunk driving-related deaths and injuries nearly three times higher than during the rest of the year.

All this adds up to the fact that the six days around Christmas are 18 percent more dangerous than Thanksgiving (the busiest travel day of the year) and a whopping 27 percent more dangerous than New Year's Eve. It turns out that combining commuters who just want to get home and start their vacation, last minute shoppers, people stressed about the holidays, and all that extra holiday cheer (read: booze) is a recipe for disaster.

This is yet another reason the emergency room is such a popular place over the holidays. According to the U.S. Consumer Product Safety Commission, in 2012 there were 15,000 ER visits directly related to festive decorating, or 250 a day over November and December. And the number appears to be increasing every year, meaning we are not taking this killer holiday seriously enough.

Jeff Diener/Aurora/Getty Images

Then there is the little issue of candles. Even people who would never have an open flame in the house at any other time of year probably light a candle or two around Christmas. And what better time to do so, considering you have what amounts to a pile of kindling standing in the corner. Even if you don't light candles, electrical problems are also common fire starters during the holidays. (It's those cheap lights again. You should have splurged on the fancy ones, Scrooge.) Between 2007 and 2011, an average of 230 major home fires a year started at the Christmas tree, resulting in deaths, injuries, and millions of dollars in property damage. And once again, not celebrating Christmas isn't necessarily a free pass. While they are less common, menorah fires totally happen as well. So the real miracle of Hanukkah might not be that the lamp burned for eight days, but that it didn't burn down the temple in the process.

Scott Cramer/iStock/Getty Images

Kathy wrote a very funny book, and you can buy it here and here.

Always on the go but can't get enough of those sweet, sweet dick jokes? We have an Android app and iOS reader for you to pick from so you never miss another article.

As 2013 draws to a close, be sure to check out Cracked's year in review because, well, we know you don't remember it half as well as you think.