Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

This comic introduces the concept of a "Graphograph" -- a made-up word defined as "a word in which a letter within the word represents a function related to the word." The character gives three examples: the "U" in "butt" is shaped like a graph of how funny the word "butt" is over the course of a day (a U-shape, implying it's always funny). The "N"s in "incontinent" are shaped like graphs of the need for diapers over a lifetime (rising and falling, suggesting increased need in infancy and old age). The "J" in "graph joke" is shaped like a graph of how angry you are over time spent reading graph jokes (a J-curve, meaning anger increases exponentially the more you read).

The humor operates on a delightful meta level. Weinersmith, who is famous for his graph-based jokes in SMBC, has created a recursive concept where the shapes of letters literally are graphs that comment on the words they appear in. The self-referential final example -- that the J-curve in "graph joke" represents increasing anger at graph jokes -- is the comic acknowledging its own potential to annoy. The invented term "graphograph" is itself a playful piece of wordplay, and the concept is the kind of nerdy, pattern-obsessed observation that perfectly fits SMBC's sensibility.