That's what Stacy thinks the new girl Annie is. And having to be Annie's partner in class is horrible too. Annie stores her snack in the wrong place, and she has no front teeth. Her whistling scares away the birds outdoors. Annie just doesn't do one thing the way everybody else does.
It's not easy for Stacy to be friends with someone who says potatoes are for breakfast. Then she tries some for herself and discovers it is fun to be different.