To be fair, this really should be expanded to the entire Frat Pack, but in my mind, it started with these two and grew quickly. You could mix and match any two of the comedians in this group and it would make sense.
The two guys behind South Park. They've offended everyone imaginable, stepped on everyone's toes, and just never seem to run out of ideas. I couldn't find a decent "Best Of..." clip so feel free to read up some of Listal's member reviews and be sure to read this terrific list of some of the show's best celebrity portrayals.