shell-2
Explanation
This comic shows a man lying in bed with his partner after sex. He addresses her apparent concern about the brevity of the encounter by saying: "Yes, it was fast. But because information travels at a finite speed there is a two-light-minute-thick shell of space-time, radiating out from this bedroom, into the cosmos, in which I am still doing you."
The joke uses real physics to construct an absurd consolation for poor sexual performance. The speed of light is finite (roughly 300,000 km/s), so information about any event radiates outward in an expanding sphere. At any given moment after the act ended, there exists a shell-shaped region of space where the light (and therefore the "news") of the event is still in transit -- meaning that, in a sense, an observer in that region would still "see" the act in progress. The man is technically correct: there will always be a region of the universe where, from an information-propagation standpoint, the sex is still happening.
This is a classic SMBC move of using scientifically accurate reasoning to make a completely ridiculous argument. The humor comes from the contrast between the intimate, vulnerable context of post-coital inadequacy and the grandiose invocation of relativistic physics. It's also funny because the argument, while technically valid, provides zero practical comfort -- his partner is right there in the bedroom where it's already over.