"To win or not to win is that ever the question? Nancy Oliver, founder of the Executive Women's Golf Association, said the issue of whether to let a client win a golf game is a touchy subject. Some people call the practice 'client golf.'"
William Ryberg, "Women grip golf as business tool," The Des Moines Register, May 29, 2000
I managed to date today's phrase to 1993, although the tone of the following citation suggests that the term was fairly well known at the time:

"HOW NOT TO PLAY CLIENT GOLF: Tom Eehlmann, general sales manager of KDNL-TV, scored a hole-in-one playing against a client, Bruce Kupper, at Norwood Hills C.C. on Saturday."
Jerry Berger, "Fighting Pharmacists Spring Into Action," St. Louis Post-Dispatch, September 24, 1993
|
A related phrase (lobbed my way by subscriber Erik Burns) is
client tennis, which is only slightly newer:

"He also gained a reputation for sometimes carrying competitiveness too far. Paul T. Stecko, now the president of Tenneco's packaging division but then an International Paper executive under Mr. Mead, recalls the time he brought two of his very best customers to join them in doubles tennis. Mr. Mead, incapable of holding back and playing what salesmen call client tennis, blasted an overhead shot at point-blank range into a customer's chest."
Allen R. Myerson, "West Pointer Commands Tenneco," The New York Times, May 15, 1994
|