Most of George Carlin's material. Lowbrow humour usually goes over the top and just ends up being irritating and plain juvenile, but that man managed to take it, still appeared very intelligent and made it funny as hell, not to mention that he has a lot of relevant and thought-provoking material. Pure genius. The best comedian I have ever seen.
Bill Hicks has a lot of material in the similar vein (some good ones) and deserves to be mentioned (also for the reason that he was one of the inspiring factors for the band Tool), but in my opinion he doesn't manage the rythym and timing nearly as well as George. He also had the tendency to SCREAM REALLY LOUD during some of his sketches. Not saying that that can't work in comedy, but in addition to the issues in timing and rythym... yeah.
South Park sometimes manages to be funny, but mostly they just are guilty of just going overboard. In general, any well-made dark humour combined with the right amount of coarseness is quite good. One more example of that: the comical drawings in Fallout 2 (and perhaps Fallout 3 as well, but I haven't played it).
Oh, and these:
http://www.stupidgsa.com/ :spin: :rofl:
