I do this to my wife occasionally when she drives and then need to run into a store while I wait in the car.
I've programmed a fax machine that had a "poll" mode to dial someone's extension every half hour.
I.T. people might appreciate this. Back when we used dumb terminals, I put a script in the scheduler to screw with a certain person's terminal at seemingly random times. Sometimes it would send a ^G (a beep) to the terminal. Other times it would cause the screen to flash. Other times it would turn on the audible key click on the keyboard.
At first, she thought something was wrong with her terminal. But the woman I did it to was a very meticulous person and after several weeks she came to me with a piece of paper that had a schedule of the dates and times of past beeps, flashes, and key clicks! She figured out it was done on purpose because there was a pattern to the times - I wasn't "random" enough I guess.
How about this one?
I waited for a co-worker to leave his desk one day. While he was in the men's room I went to his Win2k desktop PC and hit the "Print Screen" key. I then opened Paint and hit ctrl-v and created a bitmap file. I made this bitmap image his desktop wall paper and then dragged all of his desktop icons off of the screen.
When he returned, double clicking the icons produced no action. We all watched as he tried everything he could think of. I had to step in though as he picked up the phone to call the IT dept. No sense getting them on your bad side.
Just last week I went to the same guy's PC and opened his Intel Extreme Graphics GUI from Control Panel and set the display to refresh at 90 degrees rotated to the left. That one pi$$ed him off.
"I.T. people might appreciate this. Back when we used dumb terminals, I put a script in the scheduler to screw with a certain person's terminal at seemingly random times."
We used to have a disk with a script on it. You could load it onto some one's pc. As soon as they returned to work and struck a key, they would get a 'disk error' message. It would say "run disk diagnostic (Y)es (N)o. Didn't matter what key they hit next, they'd get "Running Disk Diagnostic". Then there would be some awful sounds followed by "Hard Disk Dirty Run Disk Washer? (Y)es (N)o. Once again no matter which key they hit, they'd get a series of messages about Wash Cycle, Spin Cycle, Draining Disk accompanied by washing machine sounds. Of course most folks, but not all, would catch on by this time. One person stopped by the boss's office to tell him that he'd had a dirty disk but it was cleaned now.