Sometimes I wonder if my brain and my mouth have become disconnected, and the words I intended to say have come out in some kind of alien tongue. You know what it's like: you ask a question, or comment on something, and get a totally unconnected response. A recent order made over the phone is a case in point. When the goods arrived they were the wrong colour, they were different sizes and the discount had been left off. I'm sure I said, more than once, what I actually wanted. 

It happens often with emails too.

The problem is, people tend to hear (or read) what they're expecting to. In other words, they assume that they know what's coming next. While this can be aggravating if you're trying to book an appointment etc., for writers, it can be helpful. Clichés, sayings, stereotypes and traditional forms can all act as a kind of shorthand.

If you're writing an action thriller and you say your protagonist is a world-weary ex-cop, readers will instantly build a picture of someone in their fifties with a broken marriage, probably a drinking problem and a bad attitude to authority. This can save you much description, but more importantly, because the reader will be expecting a certain look or behaviour, you can subvert the stereotype to intrigue and unsettle. What if your world-weary ex-cop is a woman who's a stickler for regulations? You have set up a new twist on the formula that will keep readers guessing and turning the pages. Change a saying like 'bang to rights' to 'bang to wrongs' and you have to read on to know what's happening.

That master of suspense, Alfred Hitchcock, teased his audience and heightened tension by establishing expectations and subverting them or delaying their fulfilment. Watch the scenes in his film Sabotage involving a bomb and a bus ride for a good example. 

Set a scene with children playing football in a back street. Cut to a speeding car swerving around the junction. A police siren is heard in the distance, approaching. The ball runs out, a child follows–everyone expects the child to be run over. Instead, the car driver brakes and the car crashes into a lamp-post. The audience breathes a sigh of relief. Then the police car speeds around the corner, clips the first car and swings into the boy. Okay, it isn't a great story, but you get the picture.

Set up a familiar scene, so the audience (or reader) thinks they know what will happen, subvert their expectations, then–bam! And bam could well be what happens the next time the wrong order arrives on my doorstep!