The correct way to punctuate a sentence that starts: “Of course it is none of my business but — ” is to place… — Robert A. Heinlein

The correct way to punctuate a sentence that starts: “Of course it is none of my business but — ” is to place a period after the word “but.” Don’t use excessive force in supplying such a moron with a period. Cutting his throat is only a momentary pleasure and is bound to get you talked about.

p. 350Source: Wikiquote · CC BY-SA 4.0