Washington ? Last month, scientists at Clemson University in South Carolina determined that applying the five-second rule to dropped food will not prevent the food from gathering bacteria.

If you’ve never heard of the five-second rule, ask any sixth-grader. “It means that if you drop something on the ground, you can still eat it if you pick it up in five seconds,” says Kiara Hopkins, 11.

“God made dirt and dirt don’t hurt,” elaborates Christopher Evans, 13. “But after five seconds, it’s nasty.”

It would seem that the Clemson research would be the death of the five-second rule. But such thinking would be based on the notion that the five-second rule is like any other rule, bound by the rule-like constraints of practicality and public good. It is not. The beauty of the five-second rule is that it is utterly pliable and that it is not about food so much as it is about yearning and disgust and gastronomic history and evolutionary wiring and the implicit social contract we make when we break (and drop) bread with other human beings.

Following the rule requires understanding its intricacies. “I would never eat a pickle,” says Anaiah Grissom, 9, “not even after one second.” She also would not eat a hot dog, a burger or a piece of broccoli, because those get dirty really fast. A Chips Ahoy, according to Anaiah, can last up to 15 seconds, and Pop-Tarts, like, never get dirty.

The tastier the treat, the longer it can be left on the floor. Cake tastes better than cookies, though, and gets germy before cookies. You can almost never use the five-second rule on cake. Parents will, however, employ it on any foodstuff with a high per-pound price: “You pick that up and eat it! You know how much that COST?”

The purpose of the five-second rule is not to protect you from bacteria but from ridicule. It’s shorthand for, “I know what I’m doing is gross, but citing this rule will allow me to eat this brownie and you to pretend there is justification for me eating this brownie.”

It’s not just for children: In a 2003 survey conducted at the University of Illinois, 70 percent of women and 56 percent of men had knowledge of the rule.