an acronym, short for Wife Beater Friday. Wife Beater being a blue Bonds brand singlet. Other colours (non-blue) are accepted under extenuating circumstances, but it's commonly known that a wife beater must be blue. Wife Beater Friday being the day that you must wear your wife beater to work. This is EVERY friday.
Employee 1: "Hey, it's WBF, where's your 'beater?"
Employee 2: "It's in the wash"
Employee 1: "Wash? you wash it? Poof!"