Malbolge is a programming language, but not just any programming language:
Malbolge is a public domain esoteric programming language invented by Ben Olmstead in 1998, named after the eighth circle of hell in Dante’s Inferno, the Malebolge.
The peculiarity of Malbolge is that it was designed to be the most difficult and esoteric programming language.
And I find it hard to argue:
This Malbolge program displays “Hello, world.”
Obviously designed by someone with Knuth’s and Einstein’s intellects, and Jack Daneils’ and Stolichnaya’s contents on tap.
And some call C++ difficult to program
Thanks to Steve for the amusing link.