“Show up, keep up and shut up” is often said to be the job of a professional golf caddy. The saying has been cited in print since at least 1992. The professional golfer Curtis Strange is sometimes given credit for the saying, but this hasn’t been verified in printed citations.
 
When Steve Williams, the former caddy of Tiger Woods, talked with the press in 2011, it was often remarked that he had forgotten his duty to “shut up.”
 
   
Wikipedia: Caddy
In golf, a caddy (or caddie) is the person who carries a player’s bag and clubs, and gives insightful advice and moral support. A good caddy is aware of the challenges and obstacles of the golf course being played, along with the best strategy in playing it. This includes knowing overall yardage, pin placements and club selection. A caddy is not usually an employee of a private club or resort. He is classified as an “independent contractor,” meaning that he is basically self employed and does not receive any benefits from his association with the club. Some clubs and resorts do have caddy programs, although benefits are rarely offered. Particularly in Europe, the vast majority of clubs do not offer caddies, and amateur players will commonly carry their own bags.
 
26 May 1992, Waterloo Record (Kitchener, Ontario), “Caddies are more colorful than pro golf tour players” by Richard Zokol, pg. C3:
They only want them to show up, keep up and shut up.
 
19 January 1995, Austin (TX) American-Statesman, “Beast of burden: PGA caddie carries weight of a player’s world on his shoulders” by Bob Riefke, pg. C3:
Show up, keep up, and shut up. The expression is a widespread joke among PGA Tour caddies, but if you were to ask certain tour players what they expect of their caddie, that just might be their ...
 
Sports Illustrated
June 26, 1995
Golf
Tim Rosaforte
(...)
“The three requirements for a caddie are to show up, keep up and shut up,” Murchison said last week. “Well, she’s never late. She’s quiet and she’s one of the few who can keep up with me. I’m a very fast walker.”
 
30 June 1998, The News (Frederick, MD), “Celebrity Cipher” by Luis Campos, pg. B6, col. 5:
PREVIOUS SOLUTION: “Basically, it’s show up, keep up and shut up”—Mike Cowan, Tiger Woods’ caddie, on his primary duties on the PGA tour.
     
SI.com
Inside Golf by Rick Arnett
My day as Todd’s caddie
Why the British Open champ named me ‘Game Show’
Posted: Wednesday July 13, 2005 3:56PM; Updated: Thursday July 14, 2005 4:40PM
(...)
I know the three clichéd rules of caddying; show up, keep up and shut up.
   
MassLive.com
Tiger Woods and Stevie Williams: Show up, keep up, and shut up
Published: Tuesday, August 09, 2011, 7:38 AM   Updated: Tuesday, August 09, 2011, 11:24 AM
By Scott Coen
Show up, keep up, and shut up. That’s what two-time U.S. Open champion Curtis Strange said is the job of a professional golf caddy.
 
But in the case of Tiger Woods and Steve Williams, they just might be words to live by.
 
ESPN
Breaking bad
Tiger Woods learned there’s nothing so dangerous as a caddie scorned
Updated: December 15, 2011, 11:53 AM ET
By Scott Eden | ESPN The Magazine
(...)
It was said with great frequency that Williams had violated one of the three great rules of caddying: “Show up, keep up and shut up.” But if Williams had broken any code, it arguably had less to do with caddies, most of whom bristle at the “keep up, shut up” mantra, than with the mores of sport. If a caddie could be considered part of a team, then Williams hadn’t “kept it in the clubhouse.” He had become a distraction. Instead of saying the right thing, Williams had said the true thing.
 
Voxy.co.nz
Golf: Mayfair’s Millions
Contributor: Stan Sutherland
Friday, 20 April, 2012 - 19:27
(...)
David concludes, “The old expression that the caddie’s job is to “show up, keep up, and shut up” is no longer true. Now the player wants to know—often in great detail—what they caddie thinks.”