Well, there really isn't such a thing as a "run-off" sentence that I am aware of, do you mean a "run-on" sentence, because if you do then you are talking about a sentence that ignores the usual rules of punctuation to separate ideas and thoughts given within a sentence, and runs them all together without so much as a period, exclamation point, or question mark to denote the end/start of a new thought, but just keeps going and going and going without and end, and includes tons and tons of commas, kinda like this sentence.... LMAO