A friend of mine set one off when we were traveling in Australia. We talked with the guard (who very 100% ralaxed) and he said that setting off the detector is incredibly easy. While he was searching my friend's purse, we were told that some of the chemicals used in make up can set it off. After finding nothing, we were free to continue. Took all of 3 minutes, no additional security, no prolonged questioning, just a simple check and go.