Answer:
Duress Code
Step-by-step explanation:
A duress code is used by an individual to make a signal when he is being kept hostage by an assailant by using it to signal others that they are in trouble.
Duress codes can also means secret passwords that allow a person to request for emergency help by entering the code when under duress from an assailant in order to trigger a silent alarm by alerting police or security personnel.
Therefore DURESS CODE was what Joe use when he walks up to a security guard with an unknown person and states a phrase. Making the security guard to call the police as the security guard believes Joe was in trouble.