In the Navy and Marines, time off work and off the ship or station is called 'liberty.' When they have a blood drive, one incentive is they give you a mess hall pass that entitles you to a prime steak dinner and then the rest of the day off, where you get to go ashore. You get liberty in exchange for blood.
"Hey, Joe, you going ashore tomorrow?"
"Yup, they're having a blood drive. I'm gonna get vampire liberty."
"Yeah? Count me in!"
"Yup, they're having a blood drive. I'm gonna get vampire liberty."
"Yeah? Count me in!"
by zhrona January 11, 2020