It's safe to say, if you find yourself in a situation where you're wired up to a polygraph machine, something has gone wrong.
And you could be in for a lot of trouble.
The accuracy of lie detector tests has been debated and speculated over for a long time.
One big flaw is the fact an honest person may be nervous - and a dishonest person may be non-anxious.
That said, while not one percent foolproof, the consensus seems to be lie-detector tests ARE still accurate.
In fact, if you wanted to beat one - and we're not recommending you do this - there is apparently one tiny thing you can do.
Doug Williams joined the police force in Oklahoma in 1972 and as part of his training, actually went to polygraph school.