A sick day, or personal day.
Named after the famous day-time television game show, The Price Is Right, which was often watched by the person who is too sick to leave the house and go to work, school, etc.
Employee: "I'm sorry, but I won't be coming into work, today. I need a Price-Is-Right Vacation.
Boss: "That's fine. Get well soon, and be sure to be to work on time, tomorrow, to let me know what happens during the Showcase Showdown"