We've all seen them: co-workers who refuse to call it a day and show up anyway, even when they're coughing or sneezing the entire time. What makes them not call in a sick day? It's called "presenteeism," but researchers are finding out this costs the company more money than if they would just not go to work at all.

Other fellow employees would probably want to reduce the chance of getting sick too, so it's really in your best interest to stay home if you're exhibiting nasty symptoms. Here's a list of five reasons to call in sick if you feel the urge coming on.

For starters, watch the color of your phlegm if you have coughing and a runny nose. If it looks dark yellow, green or brown, then stay home. It could be an infection so consult a doctor. Chills accompanied by aching joins should be enough to deter anyone from spreading the funk, as this is another set of symptoms worth following up on. The classic fever is another thing to take seriously considering that it ccould easily spread to co-workers. These are just a few examples, so head on over to the full article for a rundown.