A combination of keys that can be pressed to close a program quickly. The most well known boss key is Alt+F4, this combination can close down almost all applications with some minor exceptions such as some full-screen video games. Although Alt+F4 is the standard boss key, some other applications have other combinations as well. Most internet browsers have another combination of boss key, Ctrl+W.
When a worker is on a program that he shouldn't be on. If the boss was to simply come into the worker's office or if the worker noticed that the boss was looming nearby, the worker could simply Alt+F4 and the application would be immediately closed. If the boss was to look at the worker's computer, all would be well. Hence why it's called the boss key.
The boss key also has other benefits. If you accidentally clicked on a link to last measure
(or other shock site) to close the browser window down you could press one of the two boss keys and the browser would close.
Another boss key in Mozilla Firefox is Ctrl+Shift+W however this is a bad combination to use as a boss key for two reasons. One, if you have two or more tabs open (one containing work stuff and the rest containing the bad stuff) then Firefox puts up a dialogue box asking whether you want to save your tabs for when you next run Firefox if you have multiple tabs open so you will have to click on one of the buttons. One second can make a difference between getting away with it and getting fired!