bang in v. to call in sick to work; (hence), to take a day off from work under false pretenses. Editorial Note: This is probably related to bang the books ‘to commit time and attendance fraud,’ which at least one source indicates is part of FBI...
bang the books v.— «When I went to the field, I saw things like voucher fraud and banging the books—which means time and attendance fraud—and some of us were bitterly disappointed about that. But we rationalized that we were fighting a bigger enemy...