clouds
Explanation
The Joke
Two people are lying on the grass looking up at the sky. One says: "Sometimes I look at the clouds, and I feel they're speaking the truth to us." The other responds dismissively: "F*** you, John." The bottom panel then reveals the punchline with large text: "The cloud-shaping machine was a good use of our savings." This implies that one of them actually bought a machine that shapes clouds into messages, and the clouds are indeed literally spelling out truths -- including, apparently, insults directed at John.
The Humor
The joke operates on a bait-and-switch structure. The opening panel sets up what appears to be a classic wistful, philosophical moment -- two friends lying on their backs, one waxing poetic about finding meaning in cloud shapes. The other person's angry response seems disproportionate and rude, as if he is just a grumpy killjoy. But the reveal recontextualizes everything: someone actually spent their savings on a cloud-shaping machine and has been using it to write insulting messages in the sky. John's anger is entirely justified because the clouds really are "speaking the truth" -- and the truth is apparently not flattering to John. The absurdity of a "cloud-shaping machine" existing, combined with the pettiness of using it for personal insults, makes the punchline land.