freudian
Explanation
The Joke
Two people are discussing why so many people believed Freudian psychology. One character explains the appeal: Freudian theory tells you that deep down, humans are all monsters -- that beneath our civilized exteriors, we are driven by dark, primal urges (sex, aggression, the death drive), and that our social norms are just a thin veneer over our bestial nature. This, the character argues, is a flattering narrative because it makes people feel powerful and dangerous, like they are heroically restraining a beast within.
The other character then offers an alternative interpretation: "Or, it actually means we are here on Earth to eat and poop and occasionally reproduce, and there is nothing at all that is that deep or cool about any of it." In other words, our "animal nature" is not some terrifying dark force -- it is just mundane biological functions. The first character is deflated, and the ghost-like figure of Freud (or a representation of the id) looks equally disappointed. The final panel has the second character cheerfully concluding that if we strip away the pretense, we are all just biological organisms -- and the first character thanks them for "ruining" the mystique.
The Humor
The comedy lies in deflating the Romantic appeal of Freudian psychology. Freud's theories, while largely discredited scientifically, remain culturally popular in part because they make human nature sound dramatic and dangerous. The joke is that people are drawn to Freud not because his theories are accurate, but because being told "you have a dark, untamed id" is more exciting than being told "you are a biological machine that eats, excretes, and sometimes reproduces." The second interpretation is arguably more accurate but far less flattering, which is exactly why people prefer Freud. It is a joke about humanity's desire to see itself as more interesting than it actually is.
References
The comic references Sigmund Freud's structural model of the psyche (id, ego, superego), particularly the concept of the id as a reservoir of primal, unconscious drives. Freud's theories dominated psychology in the early-to-mid 20th century but have been largely superseded by cognitive and neuroscientific approaches. The "thin veneer of civilization" idea is central to Freud's "Civilization and Its Discontents" (1930).