A certain town has had an outbreak of salmonella, and all the restaurants are taking extraordinary measures to reassure their customers that their food is safe. One restaurant even puts out a sign saying, "Our food is untouched by human hands."

One skeptical customer watches the waiters carefully and sees that, sure enough, each of the waiters carries a pair of tongs. Whenever a customer orders anything, even a doughnut or a dinner roll, the waiter uses the tongs to pick up the item and place it on a plate.

He also notices that every waiter has a bit of yarn hanging out of the front of his trousers. Overcome with curiosity, he asks the nearest waiter what the yarn is for.

"The manager here is so strict, he won't even let us touch ourselves when we go to the bathroom," says the waiter, "so I've got the yarn tied around the ol' Johnson, and I use the yarn to pull it out."

The customer smiles appreciatively, and then frowns when another question occurs to him. "OK, I understand how you take it out," he says, "but how do you put it back in?"

The waiter bends down and whispers, "I don't know what the other guys do, but I use my tongs."