Okay, this must be a really juicy post, right? Indeed, without a doubt, to be sure, the expletives will fly. In brief, they already have.
Mostly, we think of expletives as cursing or profanity. I date myself, but if you remember when the Nixon tapes were publicized in the '70s, you'll never forget the phrase "expletive deleted," or cease to connect the word to that event. But the "more" in this post's title means more wordplay, and rhetorically speaking an expletive is a word or phrase that interrupts a sentence in order to emphasize what's being said. I am, in fact, going to eat that entire carton of triple fudge caramel sundae delight. "In fact" is an expletive meant to call attention to what the speaker is planning to do. Clearly, his story is a pack of lies; he's going to get arrested, of course. That sentence has two of them: "clearly," and "of course." I found expletives rather useful when making a point with teenagers while allowing them to save face: You will, I trust, return by 10:30 with the car in pristine condition. Of course, if you use too many expletives you may encounter more than social disapproval; to tell the truth, they tend to pad your writing. Clearly.
Another interrupter (boy my manners stink today, don't they?) is the parenthesis, and that one also means more than we typically think. The term can refer to the actual word, phrase or sentence that is placed within another sentence to offer a brief explanation of a point, not just the marks sometimes used to set it off. Parentheses are usually set off with commas, dashes, or -- yes -- parentheses, just to make things a tad more confusing. They are meant to be an addition, not a necessity, to the sentence that contains them. Frankie flunked four classes -- history, English, lunch, and study hall -- and his daddy took the T-bird away.
And we think we know what an apostrophe is, don't we? Although I seriously doubt they teach the punctuation mark in schools today anymore, but I digress. An apostrophe isn't an interrupter that explains, it's one that stops the present action to do something else, such as address "dear reader" directly. This is often done for the purpose of asking the reader to consider something or breaking something to him gently. We may think use of apostrophe is old-fashioned, but authors such as Jeanne Birdsall, in The Penderwicks, and Kate DiCamillo, in The Tale of Despereaux, use it: Did anyone think then about the Garden Club Competition? Did anyone hesitate, vaguely remembering what they'd been told over and over -- stay out of the gardens that day? No, no one thought or hesitated . . . (Birdsall, The Penderwicks). Reader, as teller of this tale it is my duty from time to time . . . (DiCamillo, Tale of Despereaux).
Which is all by way of saying -- if you want permission to use expletives and interrupt in three or more distinct ways, look no further than your standard English grammar guide. Who'd have thought Language Arts was such a racy subject? :)