A question from Yahoo! Answers:
What kind of questions are asked in the polygraph test when applying to be a cop?
There is only one kind of question that is asked during a polygraph test: a true-or-false question. You are expected to answer only yes or know.
Usually, a polygraph test starts with some calibrating questions to which interviewers know the answers (such as “is your name John Doe?” or “were you born on May 15, 1985?”). The purpose of those questions is to record your relaxed responses. Then, most questions are still completely toothless (say, “did you attend Lincoln High School?” or “are you currently married?”), but there are a few that are loaded (“have you ever taken illegal drugs?”, “have you ever owed money to a bookie?”, “have you ever had sex with a prostitute?”, “have you ever committed a crime?”) These are ones for which the interviewers want truthful answers…