During university I worked in campus IT, and we had a robust tradition of technical pranks. One day my mouse movement stopped working; clicks were fine but no c

During university I worked in campus IT, and we had a robust tradition of technical pranks. One day my mouse movement stopped working; clicks were fine but no cursor. I immediately started in tearing apart the OS of my workstation, looking for whatever they'd done to mess with it. Didn't find anything so started recompiling the kernel, thinking they'd really outdone themselves with a high-quality hack. It was only then that I noticed the sticky note over the sensor on the bottom of the mouse.