An idiom is another saying that creates a picture in your head. Idioms are quite common, and like metaphors, the words don’t mean exactly what they say. So when you say ‘I got out of bed the wrong side’ you don’t really mean that you did – it means you’re in a bad mood! And if somebody says, ‘You’ve got your head in the clouds!’ – of course you haven’t really! They mean you’re daydreaming. Great, aren’t they!