How is it done ?
For regular play on most golf courses a greenkeeper will change the cups on the green to reflect a course set up of 6 easy, 6 medium difficulty, and 6 difficult positions on the greens. For tournament play the committee running the tournament will choose slightly more difficult pins than normal usually with input from the club pro. For professional tournaments positions are picked that reflect the amazing ability the pros have so a sadist will pick the positions.