I read about it in some UK Nintendo mag then I tried it and did it. In this training mode, if you look at the end of the alley you'll see two small red lights. One on the left side, one on the right. When you get to 91 pins the barriers are lined up with them. Those red lights are buttons apparently. At 91 pins if you manage to throw the ball and it rides the barrier to the end it hits the button...big boom, instant 91 pin stike. It's the little things that matter.