TDY= Temporary Duty Assignment in Air Force-ese, Bogtrotter.
Marine Corps uses TAD.
Short term Active Duty posting or change of station.
Jack.
God bless the Marines.
By the way, here is a little humor video for you - a great combination of Full Metal Jacket and Rudolph the Red nose Reindeer.
http://youtube.com/watch?v=h-5yFNpNbSc