N.U.B. or NUB is an acronym for a long used expression in the U.S. Navy that means Non-Useful Body. Usually a term given to those recently out of school and have yet to learn the ways of being a true sailor.
Submariners in the U.S. Navy usually use this term towards those who have not qualified for submarines, an arduous task which ends in the sailor being presented his "Dolphins" and being accepted as no longer being a NUB.
All of these kids confusing the word n00b with this word are NUBs