An idiom is a group of words or slang expression which dont really mean what they say. an example from the outsiders is, johnny never cracked a book. this means johnny never opened or read a book. another example of an idiom s.e hinton uses in the novel is, she looked down on him. this was said by a girl in ponnys lab class at school when pony had pulled out his switch blade. the girl in ponys class, in other words, doesnt like pony and she thinks she is superior to pony. s.e hinton uses quite a few idioms in the outsiders.