Paper pushers around the world are familiar with paper cuts. As small as they are, they can be incredibly uncomfortable, but have you ever stopped to think about why such a tiny cut can be so painful?
There are a few reasons, starting with the fact that your hands are loaded with tiny nerve endings called nociceptors. When these get sliced by a piece of paper, your brain is the first thing that hears about it. The nociceptors send pain signals to your brain, causing the discomfort you feel after a paper cut.
Another factor behind a paper cut's unbelievable discomfort is the way paper itself is cut. As smooth as the edge of a sheet of paper might look to your naked eye, a closer examination under a microscope reveals that it's quite jagged; this makes for a sloppier and more painful cut into the skin.
Lastly, keep in mind that the wood and the chemicals used to treat the paper can become lodged inside the paper cut wound, which generates additional pain - sometimes it can even cause an infection, which produces further pain for extended periods of time.
The best thing you can do after getting a paper cut is clean it out under a sink with soap and water, and then use bandages to cover the wound so that it can't get infected. Otherwise, you might be in for even more discomfort than you bargained for.