A marriage that is for the sole purpose of one or both of the participants to gain benefits that would not be available outside of marriage to each other--quite often for
immigration or health insurance purposes as opposed to marrying for love/lust. Very common in the military as
unmarried soldiers are required to live in the
barracks.
Soldier 1: Man, I hate living in the
barracks.
Soldier 2: If you got a paperwork marriage you wouldn't have to live in the barracks. Just keep
your shit separate from hers and you're gold.