We played a lot of counter strike during my uni days and at one point I created a prank program that disguised itself as system.exe and listened for mouse movement. It would then inject random but smooth error into the mouse movement. I installed it on a friend's PC and it drove him to white hot rage. I think he destroyed a couple of mice before I owned up and bought him a new high end Logitech laser mouse (which was a novel thing at the time).