“You shall have a place outside the camp and you shall go out to it; and you shall have a stick with your weapons; and when you sit down outside, you shall dig a hole with it, and turn back, and cover up your excrement. Because the LORD your God walks in the midst of your camp, to save you and to give up your enemies before you, therefore your camp must be holy, that he may not see anything indecent among you, and turn away from you.”
This is a wonderful, enlightening verse containing, as it does, detailed instructions for proper hygiene with a clear explanation for the reasons behind it. Simply put, God does not want to step in your shit.
Of course, it goes without saying that you should wash your hands afterward. Everybody knows that, right?
"Thou hast befouled my new shoes!"