Hef Day Share definition Flag The act of spending the entire day wearing the pajamas you wore to bed the night before. Usually associated with children, college students and the elderly. "I was going run errands but decided to take a Hef Day and watch football." Hef Day by utlax October 18, 2011 0 0 Get merch Get the Hef Day mug. Buy Now — $32.95 See more merch
