The reference to "Gatling" (possibly Gatling gun, or possibly a person named Gatling) is ambiguous. "I will find you and kill you" is a pop-culture threat made famous by the film "Taken." The addition of "gatling" at the end creates either a ballistic reference or a nonsensical punchline. The joke's structure suggests that finding, locating, and eliminating you is so assured that it doesn't even require a coherent threat statement.

A screenwriter from Los Angeles supposedly noted that "if Chuck Norris says he'll find you, proper grammar is irrelevant. The meaning is clear regardless."

Internet humor adopted this: "Chuck Norris threats don't need to make sense. The message is guaranteed anyway."