pras/praz is
a term used by drones.
People say it because they're either too lazy or stupid to think of something intelligent or funny to say. Common use includes.. New P99 patch "praz!"... red recruits another person "pras!". etc Mindless with no inclination of self or surroundings. A drone.
A vet can fill you in on the details of the words origins. I've only read what they've said. It has nothing to do with how I describe its common use on the forums.