This trick shot probably originated with Rick Wright, a superb trick shot performer from the USA. It's not a difficult shot to make and with a little practice you will soon have the 8 ball flying straight into the pocket.
First you need to place your chalk on the spot and sit the 8 ball on top of it. Next get hold of a wooden triangle and place it right up against the ball as shown above making sure they're touching. At the point of the triangle, place the 9 ball and once again make sure it is touching the wood. Now, making sure that the 8 ball and the 9 ball are both exactly in a straight line with the corner pocket, place your cue ball in the same straight line, 8 or 9 inches from the eight ball. When you make the shot, you need to hit the ball medium hard and if you play it well, the 8 ball will fly straight into the corner pocket with the 9 ball following close behind. The strength of the shot is all-important as you will find. Make sure that there's nothing that the 8 ball could break behind the table as you are sure to make it fly off the table as you practice! See the Trick Shot Video