I've seen a couple of questions which use a language which has the following chracters:
What language is that?
Fish and GolfScript are also contenders.... J is also possible. I've seen a lot of GolfScript because it allows for concise manipulation of arrays and such. Fish uses the above characters much more extensively than the others.... and I confess I don't know exactly what distinguishes J syntactically.
I believe that all of them fall into the category of the Turing Tar Pit as described by @dmckee