vrrrr
Explanation
The Joke
The comic is set "40 million years ago" and shows a small prehistoric cat-like creature encountering a large, terrifying predator (which appears to be some kind of prehistoric fish or reptile with enormous teeth). The cat emits a frightened "VRRRRRRRRR!" -- a vibrating, buzzing sound. The predator comments: "There, that's the last of them. Ten thousand generations of absolute terror should have bred at last the survivors who can vibrate their kind."
The scene then cuts to "Later" -- the modern day -- where a house cat is sitting on a couch, vibrating (purring) while its owner wonders: "I wonder why they're so scared by a little vacuum." The implication is that cats' purring is actually a deeply ingrained fear response dating back millions of years of being terrorized by predators, and that their modern-day terror at vacuum cleaners is a vestige of this ancient trauma -- the vacuum's "VRRRRR" sound triggering the same primal fear.
The Humor
The comic offers a mock-evolutionary explanation for two well-known cat behaviors: purring and being afraid of vacuum cleaners. It suggests that purring originated not as a sign of contentment but as a fear response to prehistoric predators, and that cats' irrational terror of vacuums is because the vacuum's motor sound ("VRRRRR") resembles the ancient predators that traumatized their ancestors. The joke works by taking real, observable cat behaviors and constructing an absurd but internally consistent evolutionary backstory that connects them. The deadpan scientific framing of the prehistoric predator's dialogue -- speaking as though narrating a nature documentary about selective pressures -- contrasts hilariously with the mundane modern scene of a cat freaking out about household appliances.