Before multitasking made it easy to control-tab away from a goofing-off page (and when people work in offices with other people), PC games shipped with a boss key — a single keystroke that instantly hid the game and threw up a screen meant to look like real work. Press it, and your dungeon crawl became a bogus DOS prompt or a fake spreadsheet; press it again, and the game came back. One of the earliest, in a 1982 IBM software suite called Friendlyware, popped up an ASCII bar graph labeled only "Productivity" and "Time."
The idea reportedly came from Roger Wagner, in a conversation with Doug Carlston on a 1981 hang-gliding trip in Mexico that also included Apple's Steve Wozniak and Andy Hertzfeld. Wes Cherry, who wrote the original Microsoft Solitaire, built in a boss key that faked a spreadsheet or displayed random C code — until his bosses made him strip it out before release.
Sierra's Leisure Suit Larry games hid a boss key that dumped you to an instant game over, with the note "Sorry, but you'll have to restore your game; when you panic, I forget everything!"
