One prank my boyfriend liked to use against me (prior to us dating... he knows not to do it now lol) was making a file that was programmed to shut my computer down. At first it was just a batch file that was labeled something like Latin Translations or something like that, and being confused as to what it was and not knowing what a batch file was, I clicked it. He set it up so it gave me a 2 minute warning and then he pretty much made fun of me for falling for it. Eventually I learned, but then he got sneakier by hiding the fact that it was a batch file somehow... I don't really remember, and I think he labeled it with some of my current file names so I wouldn't tell the difference. In any case, it pissed me off a lot and I wanted to punch him in the face haha.