Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

This comic presents a cosmic-scale joke about the nature of the universe. Two enormous, shadowy figures (implying beings of a higher-dimensional or divine nature) stand over what appears to be the universe contained in a small vessel, like a lunchbox or container. One scolds the other, saying "Bobby, my goodness! This universe has been left out so long there are BRAINS growing in it! Clean it out!" The caption at the bottom reads: "Fortunately, humans will never know why the Universe ended."

The joke reframes all of human existence and consciousness as the equivalent of mold or bacteria growing in forgotten leftovers. The "brains" growing in the universe are us -- an accidental, unwanted byproduct of neglect. The humor derives from the radical deflation of human significance: rather than being the crowning achievement of creation, we are more akin to a hygiene problem. The punchline that "humans will never know why the Universe ended" ties the cosmic horror together -- the universe will simply be cleaned out and discarded, and we will never understand that our entire existence was just something that grew in a forgotten container.