Bottom
Explanation
The Joke
A child asks their mother why women have bigger bottoms than men. The mother, apparently a biologist or someone with a flair for evolutionary storytelling, launches into an elaborate pseudo-scientific explanation: women developed larger bottoms to stop predators, and then they consume extra calories to regenerate their "defense system." The child, researching on a laptop, then asks why men have bigger bottoms now. The mother dismissively says men are "expendable" and that is just evolution.
The comic then cuts to a later scene where a woman asks a man if it has been a while since he has had a predator attack, and he awkwardly confirms. She then says "boys are expendable too," turning the fake evolutionary logic back on men as well.
The Humor
The humor comes from the absurd pseudo-scientific framing of a mundane anatomical question. The mother invents an increasingly ridiculous evolutionary narrative about bottoms being a defense mechanism against predators, complete with calorie regeneration, which parodies the way "evolutionary psychology" explanations are sometimes used to justify random biological features with elaborate just-so stories. The punchline in the final panels shifts the joke into a flirtatious context, where the "predator attack" framing is reused as a pickup line or romantic overture, undermining the entire scientific pretense.