The cut paper

For example, a sharp razor blade makes smooth cut, leaving no foreign material in the wound. While this cut is causing the pain, the discomfort usually disappear after a few minutes. A sheet of paper, cut apart, and making other minor damage by microscopic fibers within its structure. Furthermore, during the cut paper particles remain in the wound of fibers and other foreign material, which constantly stimulate the pain receptors in the skin at the edges of the wound. In turn, a large number of receptors increases the sensitivity, and the person experiences pain even with small injuries.

Also worth noting is that since a minor cut slightly bleeding or bleeding at all, blood is not "wash away" foreign objects from the wound, and it fall new stimuli. All this causes a person pain longer than, for example, bleeding from small wounds in other parts of the body.

Source: mirfactov.com/