nostalgia-2
Explanation
The Joke
The comic plays on the common internet trend where people share things that "will make you feel old" -- typically pop culture references or facts about how long ago something happened. In the first panel (labeled "EARLIER"), a man says to his coworker Hank: "Oh man, Hank. C'mere. This'll make you feel so old." In the second panel, instead of showing a nostalgic fact, the man is laughing maniacally and saying "HAHAHAHAHA! Sudden injection of ammonia into your bloodstream!" -- implying he has literally poisoned Hank to make him rapidly age or die, which would indeed "make him feel old" in the most literal and violent sense.
The Humor
The humor comes from the bait-and-switch between the familiar, benign social media trope of "this will make you feel old" (usually involving a celebrity's age or a movie anniversary) and the absurdly dark twist of someone interpreting "make you feel old" as a literal biological process to be induced through poisoning. The comic satirizes how aggressively people share these nostalgic "feel old" posts by escalating the concept to its most extreme and literal conclusion. The reversal of chronological order (showing the punchline first, then the setup labeled "EARLIER") adds to the comedic structure by letting the reader see the horrifying result before understanding the mundane setup.