More of the Same
Where I worked we had the same policy (at least in IT). Many of the guys would forget to lock their machines when they walked away. We used to send emails out on their behalf, change their screen saver, or wallpaper to some sick image, or add audio or video files to their run or runonce in the registry. The fun part about that was they didn't even know they were pranked until they restarted their computer.
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