Pucker factor is a military slang phrase used to describe the level of stress and/or adrenaline response in a dangerous or crisis situation. The term refers to the tightening of the buttocks caused by extreme fear. If it is inadequate, the person making decisions may make them "like a robot" without considering ethics or the long-term consequences of his actions; conversely, if it is excessive, then the person "puckers"--panics and becomes unable to think clearly and effectively.
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Pucker factor Wikipedia(Text) CC BY-SA