Bacteria

Here's my theory: the more bad stuff one consumes without becoming ill the stronger they are making their immune system.
The most obvious example of this would be dropping something on the floor, picking it up, brushing/blowing it off (this step can be quite unnecessary), and consuming whatever object was dropped. Sometimes when dropped there is nothing you can salvage (CURSE YOU YOGURT!!!). Regardless, when you consume the bacteria infested sustenance and fail to get sick you are making your body stronger. Right?
Is there any validity to this or did I just watch The Princess Bride at a highly impressionable time in my life?