Joke programs are non-damaging, non-spreading, and mostly harmless programs that are not intended to cause damage to computers.
The main purpose of these programs is to annoy or entertain the user. Some of these programs have the intent to scare the user by making them think that his or her computer is broken when in fact, it is normal. They can sometimes be detected by antivirus programs since they may interfere with the normal function of a computer.
They do not infect files, nor do they actually cause damage not told to the user beforehand. Most of these programs do not replicate themselves, although they can be infected with other types of malware. However, some of these programs are damaging, such as WinFastener and Lose/Lose.