The term SPONGE (OFF OF) can be solved by two crossword solutions: MOOCH (5 letters) and USE (3 letters). MOOCH is a slang term for someone who takes advantage of the generosity of others without offering anything in return. It is often used to describe someone who frequently asks for favors or free items. USE, on the other hand, is a verb meaning to put something to practical USE. In this context, it could refer to taking advantage of someone else's resources without offering anything in return.