Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

This single-panel comic shows a map that looks like a standard political/geographic map of a region (resembling the southern United States or a similar area), but with the words "HERE THERE BE DICKHEADS" written prominently across it. This is a play on the old cartographic tradition of writing "Here there be dragons" on unexplored or dangerous regions of medieval maps.

The caption below reads "Governing Tip: Don't raise taxes on cartographers." The joke is that cartographers, being the people who literally draw the maps, have a unique form of passive-aggressive revenge available to them. If a government angers its mapmakers by raising their taxes, the cartographers can retaliate by labeling the offending region with unflattering descriptions on official maps. It is a humorous reminder that you should not antagonize the people who control how you are represented to the world.