Quoted:
Ok I see. A way to alert security you're a hostage.
Thanks.
In the Air Force there are two kinds of duress
PASSIVE: Non-compliance with standard procedures. Which could be as inocuous as a new Lieutenant showing hid ID card upside down at the LCF gate.
ACTIVE: The actual passing and receiving of the current primary duress word.
I had a 2Lt come up to the ECP at Bldg 600 at RAF Chicksands (High Security) and just start saying, "Lawnmower, lawnmower, lawnmower!", the current word. We jacked him up and the three people standing next to him in line. We got him into the ECP and asked why he passed the duress and he said, "I just wanted to see if it worked.
The word is supposed to be inserted into a normal conversation without alerting the bad guy. Then everyone gets challenged and jacked up, the passer is secured and separated, and the reason for the duress is determined.
In 1984 at Kunsan AB, South Korea, a legendary non-compliance with standard procedure occurred. A ROK gate guard was waving people in, a ROK Captian drove up and the ROK guard gave him a sharp salute. The Captain returned it and the ROK guard shot him dead. Turned out that the Captain was an NK infiltrator and had reverted to the NK style of salute in the reflex action.
You'd should've seen all the USAF pilots who saluted sharply for months after that event.