nature
Explanation
The Joke
A man encounters Mother Nature — depicted as a green-skinned woman with leaves in her hair — and expresses surprise, saying he didn't know she was real. She confirms her identity as "the protector of all things natural and beautiful." The comic then cuts to a scene where she is caught pouring something into a city's water supply. When confronted about why she's putting poison in the water, she delivers the punchline: "You know why. Humans are not natural or beautiful. You know this."
The joke operates on a simple logical extension of Mother Nature's stated mission. If she protects "all things natural and beautiful," then humanity — which has industrialized, polluted, and transformed the natural world — would logically be her enemy rather than something under her protection. She's not a benevolent guardian of the whole Earth; she's specifically hostile to the one species that has been most destructive to nature.
The Humor
The humor comes from subverting the warm, nurturing image of "Mother Nature" that typically appears in popular culture. Rather than being a gentle earth-mother figure, she's essentially an eco-terrorist carrying out a logical but horrifying interpretation of her job description. There's also a layer of dark comedy in how matter-of-factly she explains her reasoning — she's not angry or emotional about it, she simply states the obvious as if the man should already understand why she'd want to poison humanity. The comic taps into environmental guilt, suggesting that if nature truly had a personified advocate, that advocate would have very good reasons to view humans as the problem rather than the solution.