BrainFuck
Brainfuck is an amusing and minimalistic programming language which doesn't serve any real purpose except being a funny joke, challenging programmers and testing the boundaries of computer language design.
Warning! Brainfuck isn't suitable for practical use when programming!
This is a piece of source code like Ed in Brainfuck language:
+[[,][-]+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++.[-]+++++++++++++.---.+]
More information about Brainfuck language: http://en.wikipedia.org/wiki/Brainfuck
Other humor in the GNU Humor Collection.
Disclaimer
The joke on this page was obtained from the FSF's email archives of the GNU Project.
The Free Software Foundation claims no copyright on this joke.