chuck
Explanation
The Joke
The comic is a wordless four-panel strip. In the first panel, a dog is sitting on a couch reading a book titled "Animal Fun Facts." The second panel shows the book open to a page that reads: "Average Dog Lifespan: 12 Years" and "Average Human Lifespan: 80 years." In the third panel, we see the dog lying awake at night, unable to sleep. The fourth panel pulls back to show the exterior of the house at night, where through a window we can see the dog still lying awake while a human (presumably the owner) sleeps peacefully below, and the dog's thought bubble says "Good grief."
The Humor
The humor comes from imagining a dog having an existential crisis after learning that its human companion will far outlive it. Normally, the "dogs die too young" sentiment is framed from the human perspective -- we are sad that we will outlive our beloved pets. This comic flips the script: the dog is the one distressed by the lifespan disparity, lying awake at night processing the fact that its owner will go on living for decades after the dog is gone. The "Good grief" exclamation adds a layer of understated, Charlie Brown-style dismay to the dog's realization, making the existential dread feel both poignant and comedic.
References
The phrase "Good grief" is famously associated with Charlie Brown from Charles Schulz's Peanuts comic strip, which itself prominently features a dog (Snoopy). This may be a deliberate nod to that connection.