How to dress, according to the book: Stephen King wrote: "It was a clown, like in the circus or on TV . . . the face of the clown in the storm drain was white, there were funny tufts of red hair on either side of his bald head, and there was a big clown-smile painted over his mouth . . . The clown held a bunch of balloons, all colors, like gorgeous ripe fruit in one hand . . . He was wearing a baggy silk suit with great big orange buttons. A bright tie, electric-blue, flopped down his front, and on his hands were big white gloves, like the kind Mickey Mouse and Donald Duck always wore."
How to act: Pennywise isn't really a clown; he's an ancient, demonic entity, and he'll do anything to lure children to their untimely deaths. Try to toe that line between jovial and maniacal and evil.