Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

The Joke

A time traveler arrives to warn a teenager: "Bob! I''m you from the future! In five years you invent a time machine!" He explains that Bob will use the time machine to go back to when he was sixteen and relive a school dance, but his meddling causes his mom to dance with his girlfriend Chelsea, leading to embarrassment. Worse, Bob''s "changing of past timelines results in a catastrophic nuclear war 50 years later."

Bob asks if the future version is there to stop him from making the time machine. The future Bob says no -- it was totally worth it. He is actually there to warn Bob that future time travelers will keep showing up to try to convince him to stop, and he should commit to ignoring all of them: "We''ll be doing this for what will seem like weeks. Are you prepared?" Bob responds: "I will die on this hill."

The Humor

The joke subverts the classic time-travel narrative where a visitor from the future tries to prevent a catastrophe. Here, the future self fully acknowledges that his actions caused a nuclear war but considers the do-over of a high school dance so personally valuable that global annihilation is an acceptable price. The escalating absurdity -- inventing time travel just to relive a dance, accidentally causing nuclear war, and then doubling down on the decision -- satirizes human selfishness and our tendency to prioritize petty personal experiences over enormous consequences.

The final twist adds another layer: rather than being a single dramatic confrontation, the time-travel warnings will apparently come as an endless parade of future visitors, all of whom the teenager must stubbornly resist. The phrase "I will die on this hill" is both figuratively appropriate (he is being obstinate) and darkly literal (nuclear war will indeed kill people on hills and everywhere else).

References

The comic parodies classic time-travel cautionary tales such as "A Sound of Thunder" by Ray Bradbury, the Terminator franchise, and other stories where small changes to the past cascade into catastrophic futures.