i39m-going-to-kill-you
Explanation
The Joke
A person is whispering to the person next to them in what appears to be a line or row of people seated together: "I'm going to kill you tonight. This isn't part of the game we're playing. This is just me saying it. I'm going to kill you tonight." The caption below reads: "This is the best possible phrase to use in a round of Telephone."
The game of Telephone (also known as Chinese Whispers) involves one person whispering a message to the next, who whispers it to the next, and so on down the line. The message typically gets garbled and distorted as it passes through each person. The joke is that this particular message is ingeniously designed to resist distortion -- it is a direct death threat that explicitly clarifies it is not part of a game, and it repeats itself for emphasis. Even if parts get garbled in transmission, the core threat is likely to survive intact.
The Humor
The humor comes from applying strategic optimization to a children's party game. Instead of choosing a funny or complex phrase (as most people do), this player has chosen the most alarming possible message -- one that the recipients will desperately try to convey accurately because it sounds like a genuine threat. The meta-layer of the message saying "this isn't part of the game" is particularly clever, because it preemptively counters the natural assumption that anything said during Telephone is just part of the game. The comedy is in the dark absurdity of treating a murder threat as a game theory optimization problem.