boss screen

noun

a screen image within a computer game that can be activated instantly, designed to hide the evidence of game-playing, especially at 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