"Percy, we're going to Polyphemus' island! Polyphemus is an S-i-k...a C-y-k..." She stamped her foot in frustration. As smart as she was, Annabeth was dyslexic, too. We could've been there all night while she tried to spell Cyclops. "You know what I mean!" --
Don't cross out. (That is editing as you write. Even if you write something you didn't mean to write, leave it.) Don't worry about spelling, punctuation, grammar. (Don't even care about staying within the margins and lines on the page.) Lose control. Don't think. Don't get logical. Go for the jugular. (If something comes up in your writing that is scary or naked, dive right into it. It probably has lots of energy.)
"Can you spell everything?" asked Milo admiringly. "Just about," replied the bee with a hint of pride in his voice. "You see, years ago I was just an ordinary bee minding my own business, smelling flowers all day, and occasionally picking up part-time work in people's bonnets. Then one day I realized that I'd never amount to anything without an education and, being naturally adept at spelling, I decided that--"