knock
Explanation
This comic shows two people, one of whom says: "Jeez, why are you getting so tense? I'm just telling a joke." The other person, looking anxious and hunched over, thinks to himself: "...If I stay quiet he won't think I'm here." The caption below reads: "Rising social anxiety has devastated the knock-knock joke format."
The humor comes from applying the real-world trend of increasing social anxiety (particularly among younger generations) to the structure of a knock-knock joke. A knock-knock joke requires the listener to respond "Who's there?" -- but a person with severe social anxiety might instead hide and refuse to answer the door, not wanting to interact with whoever is knocking. The joke-teller can't even get through the setup because his anxious friend is treating the fictional "knock knock" as a real knock at the door and is trying to avoid being noticed. It's a clever meta-joke that uses the rigid call-and-response format of the knock-knock joke to illustrate how social anxiety disrupts even the most basic social scripts.