My all time favorite prank is getting harder to do but it is still possible.

Back in the day, most people had full size umbrellas. When it looked like rain in the morning, they would take their umbrella in to work and hang it by the handle on the wall of their cubicle.

I would loosen the umbrella (partially open while holding upside down), put hole punch chad in the umbrella, and then re-close the umbrella and hang it back up.

If it was raining at the end of the day, you knew you got the victim by the hole punch chad at the door. :-D If it wasn't raining, you knew it was just a matter of time. :-D

With the compact umbrellas, it is harder to get access to sneak chads into them and hole punch chad is somewhat harder to come by.