psyops
Explanation
The Joke
The comic depicts an alien invasion scenario. An alien declares that their advanced weapons are "no match for human ingenuity" or something similar, but then a human character responds that they do not really want to fight -- however, they must declare "the one fact that will psychologically destroy the aliens forever." In the next panel, the alien says it is "impossible" that the humans could understand their psyche well enough to do that. The final panel reveals that "all affection from dogs is actually sarcasm," which devastates the alien (and presumably would devastate anyone).
The joke plays on the idea that the most psychologically devastating weapon against any sentient being is not physical destruction but rather the destruction of a comforting belief. The specific "fact" chosen -- that dogs' affection is actually sarcasm -- targets perhaps the most universally cherished belief about the human-animal bond.
The Humor
The humor comes from the absurd escalation: the setup implies some grand, species-specific psychological vulnerability of the aliens, but the punchline reveals that the devastating fact would destroy anyone, human or alien, because the love of dogs is universally precious. The idea that dog affection might be sarcastic is inherently funny because it is so contrary to how we experience dogs -- they are seen as the most sincere, unconditionally loving creatures. The comic also works as a commentary on psychological warfare: the most effective attack is not on the body but on deeply held emotional beliefs.