You can find this exercise on page 131 of the book Synergistic Golf.
Exercise Type: PILATES
Exercise Category: FLEXIBILITY, LEGS - FEET, LOW BACK, RHYTHM - TIMING
Sit tall with legs extended slightly wider than hip width apart. Extend you arms open and out to sides. Keeping the spine lifted, exhale and drop the right arm down over the left leg as if to saw off the left pinky toe with the right pinky finger. Using your abdominals, roll up and return to starting position. Repeat 4-5 times on each side.