Used in military terminology to describe the mandatory task of providing security or
lookout for anything from an ammunition arsenal to an empty
barracks. Can last for a few
hrs or 24 hrs. Usually given at the worst possible times and weekends to remind you of why you ever joined the military.
Marine:
Woot woot!!! It's Christmas, time to go home!!!
1stSgt:
Oh fuck no! You have duty
Christmas day, don't bother going home.
Marine:FML.