A new employee calls the Help Desk to complain that there's something wrong with her password.  

"The problem is that whenever I type the password, it just shows stars," she says.  

"Those asterisks are to protect you," the Help Desk technician explains, "so if someone were standing behind you, they wouldn't be able to read your password."  

"Yeah," she says, "but they show up even when there is no one standing behind me!"