Explanation: When someone is sick that person may sneeze. A virus is a really small thing, smaller than a cell in your body, that can make you sick. So, a virus can make you sneeze. A virus is also the name of a computer program that does something bad to your computer (or uses your computer in a way that you do not want it to). This joke is funny because it uses the word “virus” in two different ways. Wash your hands!