Every day, the school cafeteria fills with exclamations of “Five second rule!” as kids drop their cookies, sandwiches and chips on the ground. The idea behind the five-second rule is that it takes a moment or so for germs to collect on your food. But the five-second rule is a myth. According to a study from 2016, bacteria and germs spread onto your food the moment it hits the ground. And certain types of food will gather more bacteria than others. A fresh piece of bread covered in jelly will gather more germs than a dry piece of toast, for instance.