I remember back in keyboarding class in high school .... our teacher knew her way around a keyboard and a typewriter without a hitch, but computers?? lol ...
By that time in my life, I had already learned Basic DOS programming pretty well, so I set up a lovely little gag.
Each computer required a DOS boot disk floppy in order to start up and load the typing program. The setup was so old that they didn't even need a site license from Microsoft, MS DOS 5.0 was already past it's support lifetime, and Windows 95 was the new thing on the block.
I modified one of the boot disks in class with a new autoexec.bat file that would boot the system normally, but at the very end it would pause and ask the user if they wished to format the hard drive (none of the computers even HAD a hard drive). It then said "press any key to continue". Once any key was pressed, the directory command would be given repeatedly as a hidden command (it would just show the disk directory) and as it progressed, more and more switches were used that would hide more and more files in the directory from being displayed. Finally, it would display a seemingly empty directory, and print the message "Your Computer Is Clean Now. Have A Nice Day. All Your Base Are Belong To Us!"
Once it was finished, the command prompt would display normally, and you could go about your business. I made 4 disks with this new autoexec.bat file and shuffled them into the pile of boot disks that everybody in EVERY class would use.
Since I was the only one in the classroom with ANY programming experience whatsoever, nobody was able to figure out what was going on ... not even the other teachers who had some experience with computers. A week later, I owned up to it, and told them that there was never any harm done, it was a simple practical joke.
