theoretical-physics
Explanation
The Joke
The comic contrasts two scenarios. In the top panel, labeled "Normal Person," a guy on a couch says "What if the universe is made of math? Whooaa—" and his friend dismisses him with "Eat some more Doritos, Max." In the bottom panel, labeled "Theoretical Physicist," the same person says the exact same thing — "What if the universe is made of math? Whooaa" — but instead of being dismissed, a publisher appears and says "Sir, may I offer you a three-book deal?"
The Humor
The joke highlights the absurd double standard in how identical ideas are received depending on the speaker's credentials. When a regular person lounging on a couch has a deep thought about the nature of reality, it is dismissed as stoner philosophy. When a theoretical physicist says the exact same thing, it is treated as a profound insight worthy of a lucrative publishing deal. The humor also pokes fun at popular physics books, many of which do essentially dress up mind-blowing-sounding philosophical speculations ("the universe is made of math") in the authority of physics credentials. The implication is that the actual content is the same — the only difference is the letters after your name.
References
The idea that "the universe is made of math" likely references the Mathematical Universe Hypothesis proposed by physicist Max Tegmark in his 2014 book "Our Mathematical Universe," which argues that external physical reality is a mathematical structure. This is exactly the kind of big-concept popular physics book the comic is satirizing.