Someone walks off without locking their computer.
You shame them by changing their wallpaper to a questionable image of David Hasselhoff.
Laughter ensues.
YouveBeenHoffed.exe [<filePathOrImageUrl>] [-r | -random]
<filePathOrImageUrl> can be the full path to an image file or a Uri to an image file.
-r will select a random image for you.