failure
Explanation
The Joke
This is a "Soonish" promotional comic. A man is stranded on a tiny desert island with a single palm tree. He puts a message in a bottle: "My whole life has been one string of failures. Please send help." The bottle floats out to sea and is picked up by a ship, but the ship's response is a missile or projectile that destroys the man's island, with a note attached reading "You misspelled 'failure.'" The man is shown in the aftermath, with the island on fire around him.
The joke is a cruel twist on the "message in a bottle" trope. The castaway's plea for help -- in which he laments his life of failures -- contains a spelling error in the word "failure" itself, which is a perfect meta-example of the very failure he is describing. Rather than sending rescue, the people who find his message respond only to correct his spelling, and they do so via destructive force. The response is both pedantic and violent, combining two types of unhelpfulness into one catastrophic package.
The Humor
The humor comes from the irony of a man whose message about being a failure itself contains a failure (a misspelling), and the absurdly disproportionate response of correcting his grammar via what appears to be a military strike rather than sending help. It is a commentary on internet culture, where people will ignore the substance of a message to focus on trivial errors, taken to an extreme physical manifestation. The "Soonish" branding makes this a lighter promotional strip, but the dark humor of the castaway's situation getting worse rather than better is classic SMBC.