"The correct way to punctuate a sentence that states: "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."
~Robert A. Heinlein
I would have paid much more attention in the grammar unit if this man were teaching it.