duvet day

noun

informal a day of leave from work that an employee is allowed to take at short notice

Word Origin for duvet day

C20: from the idea of staying in bed rather than going to work
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012