You can find this exercise on page 134 of the book Synergistic Golf.
Exercise Type: PRE-ROUND WARMUP
Exercise Category: FLEXIBILITY, HIPS, LEGS - FEET
Hold on to fixed pole of golf cart. Cross R ankle over L knee and proceed to lower hips back and down as if to sit down. You will feel the stretch around your right hip and down the outer thigh while pulling on the cart to help stretch the mid back. Repeat on other leg and frequently during your round to prevent tightening.