A KFC day is a set day of the week where you and 2/3 other mates go and stuff yourself with a family bucket for 5 people, you "3 man" the bucket and feel sick afterwards, to make it a ture KFC day you must order: One Boneless bucket with 8 pieces of chicken 4 chips and a drink and two tubes of gravy

A casual invitation / threat used by an individual that is not afraid of fucking someone up.