The beauty of this particular prank, perpetrated upon me by a student in my class, was twofold:
1. I moved the mouse. I moved the mouse again. I moved the mouse again and again and again. I checked the cord. I unplugged and re-plugged the cord. I banged the mouse. I wondered if the problem was the mouse, the software, or the hardware connecting the mouse to the computer. I shook the mouse. Only then did I turn it over and find the paper blocking the laser and the note.
2. No one ever admitted to the prank. Rather than enjoying the satisfaction of declaring victory, the perpetrator understood that me not knowing who did this would be almost as frustrating as the prank itself.
It would also prevent me from enacting revenge.
I already miss those kids so much.