E-I-E-I-Crohn's.

This story is a little old, but just so totally unbelievable that I had to share it. German researchers may have conclusive evidence that children exposed at a young age to certain microbes — the kind of microbes you would find in a barn or farm setting — may have stronger immune systems against diseases like Crohn's and ulcerative colitis. They call this they "hygiene hypothesis" and it's pretty damn interesting.

Quick and dirty article here = webmd.com