Double meaning, one. Of rising slowly and falling fast. If you do it right, you can make money faster by shorting than by doing more. If you do it wrong, you will certainly lose money. Two. It refers to the magic number, which goes up by three and goes back by one, and goes in by five and goes back by two. In other words, there is often a 30%-40% callback in the process of rising, and vice versa.