Universal
Explanation
The Joke
An alien asks a human whether any human behaviors, relationships, or cultural practices are truly universal. The human offers several candidates: community ("common, with exceptions for elders"), religion ("very popular but with drawbacks"), and other social structures. The alien keeps pressing, and the human struggles to find anything truly universal across all human cultures.
The alien then asks the human to undress. Looking at the fully naked human, the alien identifies the one truly universal human behavior: the body itself and its configurations. The punchline involves the alien observing that despite all the diversity of human cultures, races, religions, and customs, the one thing all humans share is their physical embodiment — delivered with a deadpan observation about the human body.
The Humor
The comic builds a classic anthropological setup — "what is truly universal about humans?" — and then subverts it. Instead of arriving at some profound insight about shared values or behaviors, the alien's conclusion focuses on the biological body. The humor comes from the deflation: after a sophisticated cross-cultural survey, the only truly universal thing about humans turns out to be something embarrassingly physical rather than nobly intellectual.
The alien's clinical, detached examination of the naked human body adds comedic awkwardness. The human expects to be praised for the richness of human culture, but the alien is only interested in the lowest-common-denominator biological facts.
Broader Context
SMBC uses aliens as anthropological observers throughout the series, using them to highlight the arbitrariness of human cultural norms. This comic takes the familiar "alien studies humanity" premise and uses it to poke fun at both human pretension (we want our universals to be noble) and the reality that biology, not culture, is what truly unites the species.