Reason No. 5498762548 to use the "fist bump" as a greeting instead of a handshake - Most people don't was their hands long enough to effectively clean them.

University of California, Irvine Medical Center conducted the study the shows a third of us don't bother even using soap when washing our hands. Ten percent of people in the study didn't wash their hands at all.

Pretty disgusting stuff right there!

Which makes you wonder about the people prepping your food at a fast food joint or a restaurant.

So what is the proper method for washing your hands? 15-20 seconds of vigorous hand washing is what is recommended by the Center for Disease Control and Prevention. But most people only wash their hands for six seconds at the sink.

To help in keeping the spread of germs, cold virus, etc - here's some hand cleaning tips from Linda Dickey of University of California, Irvine Medical Center.

  • Clean under nails at least once a day.
  • Keep hands away from the face.
  • Sneeze or cough into the crook of your arm.
  • After washing your hands, use a towel to turn off the faucet and open the door, if possible.

What's the proper way to clean your hands? Here's the CDC's step-by-step instructions:

  • Wet your hands with clean, running water (warm or cold), turn off the tap, and apply soap.
  • Lather your hands by rubbing them together with the soap. Be sure to lather the backs of your hands, between your fingers, and under your nails.
  • Scrub your hands for at least 20 seconds. Need a timer? Hum the "Happy Birthday" song from beginning to end twice.
  • Rinse your hands well under clean, running water.
  • Dry your hands using a clean towel or air dry them.
Last, but not least - When should you wash your hands? (Just in case you need a refresher)
  • Before, during, and after preparing food
  • Before eating food
  • Before and after caring for someone who is sick
  • Before and after treating a cut or wound
  • After using the toilet
  • After changing diapers or cleaning up a child who has used the toilet
  • After blowing your nose, coughing, or sneezing
  • After touching an animal, animal feed, or animal waste
  • After handling pet food or pet treats
  • After touching garbage