Steak and Lobster is a primarily Navy colloquial term often used if a member of the crew takes their own life. It may also be used in any other situation where something severe has happened that may drastically lower crew morale.
Sailor 1: "Do you know why we're having steak and lobster tonight?"
Sailor 2:"Yeah, our deployment got extended for a month.
Where a women's labia hangs low like when you buy a steak canadian sandwich and the bap is not big enough so some of the thinly sliced meat hangs loose resembling a women's labia.