You can find this exercise on page 44 of the book Synergistic Golf.
Exercise Type: PRE-ROUND WARMUP
Exercise Category: FLEXIBILITY, SHOULDERS
Hold the hozzle end of a golf club behind your neck with your right hand. Align the club down the back vertically and hold the grip end near your glutes, palm facing out. Pull the grip down to stretch triceps, and push elbows out to stretch chest and front of shoulders. Hold for 10-30 seconds.