Well, not exactly. But still very fun. My friends and I found that, on my school's mac network, we can forcefully "screen share" with another person while they're using it. No administrator password/account required, just the use of an account called "student" that is installed on every computer at the school. Steps to reproduce (try it without admin accounts): Open Finder. Go to the Network. Find the other computer, and open it (make sure screen sharing is enabled). Click on screen sharing in the upper right corner. Login as a non-admin account on that computer. Go nuts! Edit: More fun things to try: log on to a computer remotely and talk to people . Side note: screen sharing from computer A to computer B while B is already looking at A's screen results in one of those infinite mirror effects. Also, it won't crash your computer over short periods of time, so feel free to test it.