If you plan to commute for long on roads with cars you need to learn this term. A right hook is a term used to discribed a car that passes a biker and then immediately turns right into a parking lot or street, cutting the biker off in the process. It accounts for a number of bike-car collissions. You should learn to anticipate situations where it might happen and what you can do to save your hide when it does.

Here's a helpful link Bikesafe.