Look up INTERCAL. Brainfuck isn't too hard, just tedious. INTERCAL on the other hand was designed to be as big of a pain in the ass ass possible. People like to use the phrase "fighting with the compiler," but this is a language where the compiler is actually actively out to get you. : )

Always a fan of INTERCAL. Malbolge is a good one, too.

For more fun, check out the Esolang wiki: http://esoteric.voxelperfect.net/wiki/Main_Page

FukYorBrane is a great Branfuck variant.