Ok, now I shouldn't really be recommending this program to anyone because it basically allows you to stop your boss seeing what you're really up to on your PC.
However, for a moment, let's just substitute "boss" for partner, mother, colleague or anyone else who can't fire you from your job. StaffEye is an innovative way to allow you to see what's going on behind you as you work by using your webcam as a "third eye". It detects any kind of motion and movement and when it does so, instantly closes Windows that you've opened whether they be games, messaging programs, or anything else you shouldn't really be using. Of course, the program remains invisible - there's no taskbar or system tray icon to worry about. You simply press a customizable combination of keys to launch it into action although this will inevitably look a bit suspicious if you jump for the keyboard everytime StaffEye detects some motion. The default is "Alt+M" but you can change this to whatever you like. However, I'd strongly advise configuring it to be triggered my mouse - either a double right-click or something less obvious to reduce suspicion.
A handy program although it can be ultra sensitive to motion whether it be your boss or not and of course, it relies on your being allowed to use a webcam in the office.