ugh assembly... /me shudders

But if you want hard, try Brainfuck on for size!

Here's a "Hello World!" for you:
Code:
 ++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>. 
_________________________
"We can categorically state that we have not released man-eating badgers into the area."

-UK military spokesman Major Mike Shearer