The Worst Writing Advice EVER!

There's a great interview here:
http://margaretfieland.com/blog1/2010/10/20/interview-with-author-and-editor-linda-barnett-johnson/

The point that really jumped out at me was Ms. Barnett-Johnson's dislike of the old writing advice, "write what you know." I completely agree. "Write what you know" is the single most damaging (and most oft-repeated) bit of advice writers get. Nothing can crush creativity quite like that statement!

If you took the "advice" too literally, there would be NO speculative fiction (fantasy, horror, sci-fi), because all spec fiction is imagining the unknown. The whole genre of spec fiction would cease to exist!

My current work in progress (spec fiction, by the way) is set in western North Dakota. I have visited the area, so I am slightly familiar with it. But I wouldn't say I "know" the area; that's what Google is for. Thanks to some research, I was able to discover that the characters in my book are going to have to drive almost 100 miles to find a McDonald's, Burger King, or Starbucks (which is an important plot point). If I wrote only what I know, then all my characters would be in Eastern North Dakota where you're never more than 20 miles from a McDonald's. But thanks to Google, anything I don't know, I can find out.

And ignoring that old chestnut of writing advice seems to be working for me. Almost every short story that I've had published has a MALE lead character. So I don't even write in my known gender, lol.

So what do you think? If you're a writer, what's the worst piece of writing advice you've gotten?