I am jelly of some of my friends who got really good at programming in high school. One dude managed to replace the keyboard drivers for every keyboard on the entire network with garbage, so that if they plugged in another keyboard, it still wouldn't work. He also gave his English teacher a "wacky mouse", where she would be presenting something and at some random time her cursor switched and behaved as if attached on the end of a spring. She would often inspect the underside of the mouse in response to this problem.