Germs have you surrounded, but you can still fight back

[snopes]

What about the notion that we can build stronger immune systems by exposing ourselves to lots of crud?

Sorry, epidemiologists say, it's an urban myth and an excuse used by bad housekeepers. Not washing your hands after you sneeze or neglecting to wash the kitchen counter will not make you more hardy. Just less healthy.

http://www.bendweekly.com/news/3499.html