What is sig?
sig meaning in Military or Military Slang terminology / glossary / dictionary is:
(U.S. Navy) A signature on a qualification card (a card that shows you are ready to stand a particular watch) . There are many, many “qual cards” in the Navy that must be completed before being allowed to take an exam or be interviewed by a board to be qualified to stand a particular watch or role. Some qual cards and their individual sigs can be easy or extremely difficult to obtain. In some cases a junior Sailor going for a sig may not only have to prove his/her knowledge to a senior crewmember, but also do something extra for that signature–such as performing a minor menial task or bringing a small bribe like a can of soda.