Cursing, Darn it
Two master rules:
1) Every word must advance the plot, reveal character, or support the theme.
2) If it's wrong and it works, it isn't wrong.
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I've used vulgarity, profanity, and obscenity in my works from time to time, as I thought necessary.
See, for example, <A HREF="http://www.amazon.com/exec/obidos/ASIN/0812568591/ref=nosim/madhousemanor/" target=_new">Tiger Cruise</A> and <A HREF="http://www.amazon.com/exec/obidos/ASIN/1931013098/ref=nosim/madhousemanor/" target="_new">What Do You Do With a Drunken Sailor</A> (both by me writing as "Douglas Morgan"). In the first, a techothriller, the level, kind, and freqency, varies by the characters' social class, education, and the situation. The second is a scholarly non-fiction work, where the subject demands the language.
Other novels have had more or less, but less more than more, and then often quite mild.
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This calls to mind the joke about the dirtiest limerick in the world:
A man comes home from a night out playing poker with the guys, laughing his ass off.
"What's up?" his wife asks.
"I just heard the funniest limerick in the world," the guy says.
"So, tell me," his wife says.
"I'm sorry," he says, "but I can't tell you. It's just too dirty."
"Look," his wife says, "I know all those words. I use most of 'em myself, and I've done quite a few of them too, if you know what I mean. Tell me the limerick."
"No," the guy says, "It's just too filthy."
"Okay," his wife says, "tell you what. Just leave out the bad words and I'll fill it in for myself."
"Okay," the guy says:
Blank blank blank blank blank blank blank blank
Blank blank blank blank blank blank blank blank.
Blank blank blank blank blank
Blank blank blank blank blank
Blank blank blank blank blank blank blank fnck."
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For an example of a novel that uses unrelenting vulgarity, crudity, profanity, and obscenity to reveal character, advance the plot, and support the theme: <A HREF="http://www.amazon.com/exec/obidos/ASIN/0380692600/ref=nosim/madhousemanor/" target="_new">No Bugles, No Drums</A> by Charles Durden.
If you haven't read it, you ought to.