Conversations such as this. (I overheard this over the walkie talkie.)
Duty-mate: There is a blue liberty van at my location - should I let him through?
(For your information a liberty van is a van which brings foreign ship personnel out for liberty - liberty is a naval term meaning the granting of 'leave' from his post at the base.)
Security officer on duty: Is it a white Mercedes?
Duty-mate: It's a blue liberty van.
Security officer on duty: What is it's purpose?
Duty-mate: IT'S A LIBERTY VAN.